When working with WSUS, I kept getting an error every time I tried to do anything with WSUS (uninstall, reinstall, start the service, start the program, etc.). The error reported that the mscoree.dll file was missing or not installed correctly and reinstalling the program may fix this error. This dll file is related with the .NET framework. Reinstalling .NET 2.0 framework fixed the problem without having to reinstall WSUS.