If you’re running an x64-based version of Windows Vista or of Windows Server 2008 on a computer that has multiple Intel x64 processors or has an Intel x64 multi-core processor. When you try to install Windows Vista SP2 or Windows Server 2008 Service Pack 2 on the computer, you receive the following Stop error message: Stop 0x0000003E (parameter1, parameter2, parameter3, parameter4) MultiProcessor_Configuration_Not_Supported. This issue occurs because some processors on the computer report support for some unsupported feature sets. Therefore, when the system uses these feature sets, a Stop error occurs. This situation can occur if incorrect processor packages are used or if the BIOS incorrectly enables a processor erratum. Microsoft is working to resolve the problem, noted KB973879.