I assume that you're talking about the Windoze Blue Screen of Death?

As to what caused it? I would look and see if you've installed any new programs recently as they could have arfed something up. I doubt it's anything on EoFF. Have you accepted any applets or the like recently? They could have put crud on your computer that is giving it problems. Basically, think about anything you're done to your computer just before the blue screen problem arose, as that's probably what caused it. You might also want to run and updated virus scan, spyware and so forth to make sure nothing malicious is on your machine.

Or, as several people on these boards like to preach, you could install Linux on your machine to solve the problem.