When you get a bluescreen fault there is a code on the screen like, 00x000000034. Do a search on microsoft website for help/info on your code. Or post the code on this site for more help.
It could be your pc over heating, so hover all the inside of your pc, inluding in the ribs behind the fan on the mothboard.
If it is a heat fault download "speedfan 4.38" to keep an eye on your temps, it's free software.
Erk, July 2009