Just to elaborate on Herk's comments:
The 'Blue Screen of Death' (or BSOD) is refered to by Microsoft as a Stop Message. They can occur for many reasons. In order to diagnose it's cause we need as much info as you can give about the stop message. Please write it down and post it back here the next time it happens. In particular, it helps to have the somewhat cryptic series of numbers about half way down the blue screen that have this sort of format:
0x0000008E (Followed by four other sets of numbers in parenthesis.)
It is also helpful to know the answers to these questions:
- What are you doing when this happens (are you on line, starting the computer, etc).
- Does it always happen at the same time?
- Is it always the same message, or is it a different set of numbers each time?
- Have you added any hardware or software lately?
- Are you experiencing any other buggy behavior from this computer (such as it runs slower than it used to, etc)?