I'm in the process of upgrading a VS2005 project to VS2010, and it is giving an error...

Code:
2>C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\include\wincrypt.idl(47): error MIDL2025: syntax error : expecting a type specification or a storage specifer or a type qualifier near "WCHAR"
2>C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\include\wincrypt.idl(47): error MIDL2026: cannot recover from earlier syntax errors; aborting compilation
2>LINK : fatal error LNK1240: failed to compile IDL content
I have no idea what these IDL files are, and I'm not knowingly using wincrypt anywhere, but there must be a library somewhere using it.

Any idea on what this means, or how to fix it?