This one has been bugging me for a couple of weeks and I just managed to find a fix. Right-clicking on the start button and pressing Windows+X failed to do anything.
1) Open up command prompt and run:
xcopy %SystemDrive%UsersDefaultAppDataLocalMicrosoftWindowsWinX %userprofile%AppDataLocalMicrosoftWindowsWinX /e /y
2) Log out and log in again. Everything should work as expected.