diff --git a/visualc/sharedspice.vcproj b/visualc/sharedspice.vcproj
index adc4196e9..b324d9870 100644
--- a/visualc/sharedspice.vcproj
+++ b/visualc/sharedspice.vcproj
@@ -24,7 +24,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\conf.obj del $(ConfigurationName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -117,7 +117,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\conf.obj del $(ConfigurationName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -210,7 +210,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\conf.obj del $(ConfigurationName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
diff --git a/visualc/vngspice.vcproj b/visualc/vngspice.vcproj
index 83aa93849..933356023 100644
--- a/visualc/vngspice.vcproj
+++ b/visualc/vngspice.vcproj
@@ -28,7 +28,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -114,7 +114,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -201,7 +201,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -293,7 +293,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -384,7 +384,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -469,7 +469,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -556,7 +556,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -647,7 +647,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -739,7 +739,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -831,7 +831,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -924,7 +924,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -1016,7 +1016,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
diff --git a/visualc/vngspice.vcxproj b/visualc/vngspice.vcxproj
index da6568139..95795a69d 100644
--- a/visualc/vngspice.vcxproj
+++ b/visualc/vngspice.vcxproj
@@ -197,7 +197,7 @@
   </PropertyGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <PreBuildEvent>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -237,7 +237,7 @@
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
     <PreBuildEvent>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -317,7 +317,7 @@
       <TargetMachine>MachineX86</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -367,7 +367,7 @@
       <TargetMachine>MachineX64</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -375,7 +375,7 @@
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='console_debug|Win32'">
     <PreBuildEvent>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -414,7 +414,7 @@
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='console_debug|x64'">
     <PreBuildEvent>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -493,7 +493,7 @@
       <TargetMachine>MachineX86</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -541,7 +541,7 @@
       <TargetMachine>MachineX64</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -587,7 +587,7 @@
       <TargetMachine>MachineX86</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -638,7 +638,7 @@
       <TargetMachine>MachineX64</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -684,7 +684,7 @@
       <TargetMachine>MachineX86</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
@@ -732,7 +732,7 @@
       <TargetMachine>MachineX64</TargetMachine>
     </Link>
     <PreBuildEvent>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
diff --git a/visualc/vngspice_fftw.vcproj b/visualc/vngspice_fftw.vcproj
index 55a8e75e5..6c888c03f 100644
--- a/visualc/vngspice_fftw.vcproj
+++ b/visualc/vngspice_fftw.vcproj
@@ -28,7 +28,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -116,7 +116,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -205,7 +205,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -299,7 +299,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -392,7 +392,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -479,7 +479,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -568,7 +568,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -661,7 +661,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -755,7 +755,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -849,7 +849,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -944,7 +944,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)\$(PlatformName)\conf.obj del $(ConfigurationName)\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x86 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll32\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
@@ -1038,7 +1038,7 @@
 			<Tool
 				Name="VCPreBuildEventTool"
 				Description="Recompile conf.c with actual date, invoke win_bison"
-				CommandLine="del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
+				CommandLine="if exist $(ConfigurationName)64\$(PlatformName)\conf.obj del $(ConfigurationName)64\$(PlatformName)\conf.obj&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1&#x0D;&#x0A;..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1&#x0D;&#x0A;lib /machine:x64 /def:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.def /out:$(ProjectDir)fftw3\fftw-3.3.3-dll64\libfftw3-3.lib"
 			/>
 			<Tool
 				Name="VCCustomBuildTool"
diff --git a/visualc/vngspice_fftw.vcxproj b/visualc/vngspice_fftw.vcxproj
index a6804c7ac..e161561d3 100644
--- a/visualc/vngspice_fftw.vcxproj
+++ b/visualc/vngspice_fftw.vcxproj
@@ -202,7 +202,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -251,7 +251,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)64\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -301,7 +301,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -355,7 +355,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)64\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -413,7 +413,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -460,7 +460,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)64\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -510,7 +510,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -563,7 +563,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)64\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -619,7 +619,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -673,7 +673,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)64\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -732,7 +732,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)\$(Platform)\conf.obj del $(Configuration)\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)\$(Platform)\conf.obj;%(Outputs)</Outputs>
@@ -786,7 +786,7 @@
     </PreBuildEvent>
     <CustomBuildStep>
       <Message>Recompile conf.c with actual date, invoke win_bison</Message>
-      <Command>del $(Configuration)64\$(Platform)\conf.obj
+      <Command>if exist $(Configuration)64\$(Platform)\conf.obj del $(Configuration)64\$(Platform)\conf.obj
 ..\..\flex-bison\win_bison.exe --output=inpptree-parser.c --defines=inpptree-parser.h ..\src\spicelib\parser\inpptree-parser.y || exit 1
 ..\..\flex-bison\win_bison.exe --output=parse-bison.c --defines=parse-bison.h ..\src\frontend\parse-bison.y || exit 1</Command>
       <Outputs>$(Configuration)64\$(Platform)\conf.obj;%(Outputs)</Outputs>