yesterday i was playing a game of civilization 4 and all of a sudden i had a massive graphical error the screen went all blocky and my PC completely froze. I restarted my PC and launched the game again, then during the intro the graphics error came on, i restarted again, and installed the newest Nvidia drivers and all. after that the graphics error still happend when I launched the game again and from then on evey screen has the blocky graphical error, from boot up and windows wont load. now my question is: is my Graphics card toast? is it a virus (i did not get any warning from AVG or anything) or something else?