Had that once (9600GT) after updating drivers... And I also reinstalled the game and found that it wasn't the problem. Then I got pissed and just cleared the graphic card and all it's drivers to re-install the damned thing and it worked. Never understood what had gone wrong though so it may or may not fix your problem. I was going to recommend you use the Driver Cleaner (
www.drivercleaner.net) tool but just realized it ain't free anymore so I'd suggest finding an alternative... Or hopping by your favorite torrent search engine to see what you can find
