If you install Windows SDK for Windows Server 2008 and .NET Framework 3.5, on top of Visual Studio 2008 SP1, some CRT files’ll revert  back to RTM version. This can cause conflicts when you install patches or updates such as Security Update for Microsoft Visual Studio 2008 SP1: July 28, 2009 (KB971092), which may lead to compile errors. To resolve: Ensure that you’re using Visual Studio 2008 SP1 version of CRT by installing Windows SDK for Windows Server 2008 and .NET Framework 3.5 first, then re-installing Visual Studio 2008 SP1. Then apply Security Update. Caution: Running “Repair” on the Windows SDK’ll cause the CRT files to go back to RTM state and should be avoided.