Hi and welcome
First, try another anti-virus product - see this thread:
http://www.pchelpforum.com/forum/ind...pic,131.0.html
Next, get a piece of software that tells you your motherboard and
cpu temps...your problem could be heat related. Here is one suggestion:
http://www.almico.com/speedfan.php
Do you get a "countdown" message when your PC is about to re-boot?