computer randomly reboots

On a friends machine, with the specs of:

400 watt antec psu, known perfect condition
abit vt7 chipset via apollo pt880
crucial 256x2 DDR ram (total 512MB, identical pc3200 sticks, single/dual channel, same problem)
xp pro service pack 2
nvidia geforce4 mx 440 (microsoft drivers... eww)
western digital 80gb 7200rpm
etc..

the computer randomly hard reboots

so i tried adjusting the voltages on the ram, using different ram slots, single/dual channeling the ram, and even just using one stick of ram, then the other, to no avail. so i ran a ram check and it comes up with errors on the ram if run for 8+ hours, which im sure is not good, but in my personal machine the ram ran without any problems (did not run ram test, computer runs stable though)

so TWICE when the computer was starting up now its gone to the windows xp loading screen, but in like 8 bit color and freezes on that screen, but if i leave it like that, you hear the default windows boot sound shortly thereafter, like the video card is just not transmitting the data it gets from the rest of the comp.

the computer is spyware free, and i've even tried a format to see if it would solve the problem... well it didnt. im led to believe that the temps are ok. i cant imagine the ram overheating at stock voltages, the processor is decent via the bios monitor, leaving just the vid card in question. but this happens whether the side cover is open or not on the computer, and regardless of the temp in the house. but i've noticed that the computer restarts more frequently if you are listening to music, or watching an avi file of high quality, but this is not required to do it, it will sometimes reboot when idle.

if anyone can shed some insight into this please let me know

 

oh, and its a pentium 4 2.4 GHz socket 478

 

1)mobo is not touching anything, the risers are properly installed
2)power is stable, runs through a surge protector at the moment, but does the same with my UPS connected
3)if i run memtest86 it comes up with a few memory errors but only after prolonged use... i doubt both modules are bad though considering the problem persists even if only one of the sticks are in, and it doesnt matter which memory slot, they all have the same effect

 

Go to Nvidia's web site and down load the proper drivers, remove the drivers you have and in stall the new ones. Make a normal vga work first or you'll be in the dark. Drivers are free
Mark

 

Go to System Properties, advanced tab, startup and recovery settings.

Uncheck atuomatically restart. Find out what the stop error is, or debug the memory dump.

 

computer randomly reboots I am not new at this but I guess I could use a little help. In your reply you mentioned debug the error. Can you give a bit of a headsup on how to do this? I have an Asus a7nx NForce2 that seems to have issues I have swapped memory simms and p/s with another similar machine but the unwanted crash reboot seems to be getting worse. About the only clue I have is that on a CPU test it seemed to randomly fail cache, but after swapping p/s it ran flawlessly for over an hour? Anyway I am cleaning the cpu cooler and preparing to swap it out but I seem to be running out of parts to swap. The PC is not really that old but has had some history since SP2, some oddity called shlwapi.dll err pardon my spelling. I cannot seem to get a Bios upgrade from Asus, (thanx for nothing) But when I get it back together in a bit I plan to reinstall Windows fresh again. Before I am forced to scrap the mobo does any geekly friend out their have any suggestions?
Corred