Did that... still does not work.only one or all games affected? If only one game, you could try to delete it's files and download them again.
Have you checked this: http://www.edge-gamers.com/forums/showthread.php?t=33976
Try verifying the integrity of the data/game files through steam (right click the game in your libray then there should be a tab for it - cant remember exactly, haven't done it in a while).
