I was having the following command in my post build event command line:
"$(MSBuildBinPath)\msbuild.exe "$(ProjectDir)YUICompress.msbuild" /p:ConfigurationName=$(ConfigurationName"
and it was giving the following error:
'C:\Program' is not recognized as an internal or external command,
The solution was actually pretty easy, I just had to surround the call in quotes."$(MSBuildBinPath)\msbuild.exe" "$(ProjectDir)YUICompress.msbuild" /p:ConfigurationName=$(ConfigurationName