If you recently installed the Office 15 public preview alongside Visual Studio 2012 RC, you more than likely encountered the following error:
It seems Microsoft is well aware of this issue and has issued a patch for Visual Studio 2012. It apparently has something to do with the Office 15 preview breaking your VS2012 install… you’d think Microsoft would have tested this and fixed it before release, but I guess not.
I actually ran across this issue earlier today and figured it was a problem with the Visual Studio installer. After reinstalling, uninstalling, and installing again I eventually went and searched online for the issue. Thankfully, I was not the only one with this issue and I received the link mentioned above via a blog post at ACS Blogs.
If you are experiencing this issue, the above patch should work for you.