Check your ram, do you have another stick to try in the system? I have had countless people come to me with your problem and 8/10 times its that there ram has gone bad. The other 2 are Driver problems as abearaware said, Conflicts as mtsgsd said or finally your Hard Drive getting bad sectors and crashing.
Those are the only hardware problems I have seen to cause a crash such as this (unless I am forgetting something....could happen
) But the other thing to check is the heat in your system, make sure your vid card, proc and northbridge are not too hot.