1. Increase your virtual memory and check if your CPU is provided sufficient cooling. To check install 3D Mark and PC Mark and do the test to check if it is able to go stress. If it is not able to go through than I think your heatsink is not providing sufficient cooling
May be your computer is infected with a drwatson32 worm which automatically started whenever you end a game. Get yourself a firewall and deny to run its process whenever you end a game. For me Zone Alarm 8 is the best. Also run a full antispyware - antivirus scan.
Download Noob Killer and do a 8-X Kill. It may solve your problem.
Link:
http://www.freewarefiles.com/Noob-Ki...ram_42299.html