I am using Visual Studio Ultimate 2012 SP1/Update 1 under Windows 7 Ultimate 64-bits. I am creating a solution that works with FSUIPC to connect to Microsoft Flight Simulator X.
For that I must use a third party (binary only) .NET library called FSUIPCDotNetClient which is a DLL named "FSUIPCClient.dll" Since MFSS is a 32-bit application the FSUIPCCLient is also a x86 library and so is the underlying FSUIPC.dll (from Peter Dowson).
FSUIPCClient, Version=2.3.4765.4, Culture=neutral, PublicKeyToken=null
For this external assembly (the only one) CORFLAGS.EXE confirms that it is okay (Version: 4.0.30319, CLR HEader: 2.5, CorFlags: 0x3, ILONLY: 1, 32BITREQ: 1, 32BITPREF: 0, PE: PE32)
I was having this issue in another project and couldn't get rid of it. I had the developer of the FSUIPCClient.dll custom build me a version of his library targetting .NET 4.0 and he has it set o x86. I currently have TFS Express 2012 but the problem also surfaced BEFORE I installed TFS 2012,