Does the PC work with other games?
I had a similar problem with my old PC, turned out id let windows find the driver when i first got the PC, and it had picked one that seemed fine but infact was not when you got it to do something a bit difficult.
I still had the CD for my graphics card and i installed the driver from there manually and it was fine..
The driver will probably be on the website of your graphics card, even if you have the right one it may be corrupt or something, try reinstalling it anyway.