My computer:

Win XP Pro
GA-7VAX motherboard (made by gigabyte)
AMD Athlon 2100+ (1.7 ghz)
266 fsb
512 DDR 233
400watt Antec power supply
LeadTek geforce 4 ti4600 graphics
seagate 80 gb 7200 rpm hd
seagate 40 gb 7200 rpm

My computer randomly restarts and I have been unable to figure out why. It is not overheating - I am running at 45 c tops. The thing that is most confusing is that sometimes it will run fine for a few months and then begin restarting randomly again. Usually is restarts when I have it on but I am not activly using it, and then restarts before even finishing POST a few times, then goes back to os. I have had this problem while using winxp, win2k, and mandrake9. The other thing that is very confusing is that when I am using it the most common time it restarts is when use the mouse to scroll down a page. I move the wheel one click and it restarts. That is not what always causes it...just some of the time.

As you can see, this is a pain in the ass and I have no idea what to do about it. I have checked all connections, even went so far as to take everything out of the box and rebuild it. During that I took the heatsink off the processor and cleaned both, then put more thermal paste. It still restarts.

Any help would be great.