VS 2013 Professional - Version 12.0.31101.00 Update 4
All of a sudden, whenever I try to open a project (MVC project or Python project), I get:
I can't leave a comment on Murat Yıldız's answer so this is the next best thing. His solutions works great. I opened the Visual Studio Command Prompt as an administrator and ran from the command prompt:
C:\WINDOWS\system32>devenv /resetskippkgs
It worked like a charm.