[{HVY-E}Jinxx]

Without actually being able to test your ram it's hard to say, but my best guess is you've stumbled across a bad memory block on one of your sticks of ram.

Try D/Ling one of the free stress test programs out there and run a test on your system ram and your video ram. That should be the first place to start. Then start looking at reinstalling the whole game to see if the problem persists.

You can find some really good memory checkers and stress programs on "Ulitimate Boot CD" and "Emergency Boot CD". Both can be found on Sourceforge.net.