I had some serious issues last night with vs 2012 professional and ultimate. (Couldn’t get it to generate files on creation of a new project) A quick installation of vs 2013 express solved the issues.
It would be possible to use the visual studio 2010 SP1?
I have VS2012 Pro and have been able to build the complete engine and run it, and run other projects with no problems so far.
Make sure you get the Optional.zip file from https://github.com/EpicGames/UnrealEngine/releases/tag/4.0.1-release .
The only issues I had were when running GenerateProjectFiles.bat: First I needed to install Windows SDK v8.1, and then I needed to modify a UnrealEngine\Engine\Source\Programs\UnrealBuildTool\Windows\UEBuildWindows.cs to build for 2012 and not 2013 (posted on AnswerHub here: GenerateProjectFiles.bat fails for VS2012 because of UnrealBuildTool set to 2013 - Programming & Scripting - Epic Developer Community Forums ).