Is your IDE screwed?
I recently uninstalled some non-functioning VS.Net add-ins, that really screwed up my IDE and i started getting these messages on build
"Load of property 'AllowUnsafeBlocks' failed."
"Load of property 'ApplicationIcon' failed."
"Load of property 'AssemblyKeyContainerName' failed."
"Load of property 'ApplicationIcon' failed."
"Load of property 'AssemblyKeyContainerName' failed."
and so on...
All projects got the Output type set to Application and ofcourse i could not build, the csproj files were all ok so obviously it was the IDE that was screwed and this just one week from release ... aaargh!!
Anyways if you ever face this problem this link saved my butt
Basically what you need to do is register csproj.dll all over again
The suggested solutions were
regsvr32 "C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\vcpackages\csproj.dll"
regasm "C:\Program Files\Microsoft Visual Studio .NET 2003\Common7\IDE\PublicAssemblies\VSLangProj.dll"
devenv /resetskippkgs
The first one worked for me.