Iv got the same problem with my computer suddenly shutting off for apparently no reason. Sometimes it takes 20 minutes, other times it takes 8 hours. I cannot believe that limewire can overheat my system while some of the most graphic intensive games do not.

windows XP
2.4ghz p4
100gb hdd
geforce 4 4600 - yea, shes old, but still runs the new games
1gig 2700DDR
450watt power supply

no viruses and no adware found on last run.