Originally posted by bmxfreakrider
Sounds like you are having an overheating problem caused by dust. The reason it shuts down less in linux is because linux is not as intense as windows. To fix it all you have to do is open the computer open and blow all the dust out of there. what type of computer is it? a custom "home build" or a prebuild (dell, hp, compaq, gateway, etc...)
just clear all the dust out and that should fix it.
I agree that its probably a heating issue, and as much as dust can cause it, simply cleaning it isn't always a fix.
Machines will also run warmer as they get older. Go get a copy of speedfan to keep track of temperatures in your case. Get a can of air, and clean the dust from the inside of the case. Afterward, pay attention to the temps from speedfan.
If your still seeing heat issues, you may want to look into a better heatsink and fan.