Possibility #5: Overheating
If you’ve run through all of the preceding possibilities and continue experiencing frequent crashes, a hardware issue could be to blame. An easy one to rule out is overheating. A computer’s CPU, or central processing unit, includes a fan that is designed to keep it running cool. Sometimes, the fan wears down and doesn’t work as efficiently; other times, it’s just not able to handle the work that your computer has to do. In either case, buying a bigger, better fan isn’t very expensive. If it puts an end to your PC crashing problem, it will have been more than worth it.
Don’t Put Up with Frequent Crashes!
As discussed, frequent computer crashes can be triggered by a wide variety of issues. Luckily, many of these issues are relatively easy to remedy. Work your way through the preceding list; chances are, you’ll be able to pinpoint the problem and put an effective cure to work. Nine times out of ten, a computer simply needs a little bit of routine maintenance to get it back on track again. In the future, keep these points in mind. Any time you buy a new computer, keep up with its basic maintenance right from the get-go. By doing that, you could avoid “blue screen of death” and crashing problems altogether – and that’s something that you’re bound to appreciate!
source:
http://www.computertips.com/pc-troubleshooting/