[Javelin]

This has just started to happen today, my computer is randomly restarting all by itself.

The night before, I just left my computer on overnight as I was torrenting some files, but today I can be doing something simple such as playing a non-taxing game (Roller Coaster Tycoon in my example), or just internet browsing when my computer decides to restart. There is no blue screen or anything when this happens, my screen just goes black and I get to the POST screen.

Sometimes my computer will reboot before Windows even loads, or before it finishes loading. Other times, I can stay in Windows for a while before my computer just decides to reboot on its own. I opened my case and shuffled some of the cables around to make sure that nothing is touching any of the hardware, but it doesn't seem to have helped. My CPU and GPU temperatures are fine, CPU idles at 48C (which for idle is high, but that's due to a mistake I made, its been running fine the past two years almost), and GPU idles at 50C, going up to 68C at load. I'm not sure what it can be at this point, but my hard drive isn't making any clicking noises or anything, and my PSU seems to be fine as well, however I can't give an accurate statement as I don't know how to diagnose either piece of hardware.

Any advice that you people here can give would be much appreciated.

My System Specs:

Intel Core2Duo E6300 @ 2.5GHz
GIGABYTE GA-965P-DS3
G.SKILL 2GB DDR2-800 @ 4-4-4-12
ATI Radeon HD 4850
OCZ GameXStream 600W PSU
Seagate Barracuda 250GB HDD

EDIT: So, I decided to unplug my Wireless Internet PCI card to see if the problem could be a trojan, and that seems to be the problem as my computer has not rebooted at all.

[Nitestick]

if your error settings are set to automatically reboot you won't see a BSOD unless you're paying attention or the computer freezes. i'm thinking there may be a problem with that WiFi card that is causing the computer to crash...as you already seem to have identified.