Computer Restarts Unexpectedly

My computer restarts unexpectedly at different times. Sometimes I'm browsing the internet, playing music or doing nothing at all. My PC is brand new, custom built. A friend of mine helped me build it and he has no idea what's going on. I turned off the option for my computer to automatically restart and now I get the BSOD whenever it restarts. One time the BSOD said this "IRQL_NOT_LESS_OR_EQUAL" There's also a memory dump. I'm thinking it's driver or hardware related but i'm not sure. Possibly it's because my motherboard has 24 pins while my Ultra X Connect Power supply only has 20 pins. Here's a general overview of my specs if it will help:
ABIT AN8 SLI motherboard
2x 512 Kingston PC3200 Ram
EVGA GeForce 6600 LE
300 GB 7200 RPM Seagate Baracuda HD
Lite On 16x DVDRW DL
500W Ultra X Connect PSU
AMD Athlon 3700+ cpu
Linksys WMP54GS Wireless G PCI Adapter

 

That could be the case, as it's not receiving sufficient power but also the driver conflict seems relevant too.
Check all your drivers are up to date from nVidia.com as this might help, and what software has been installed since the problem has occured. I found that when I installed Blackice firewall on my pc I would get the same problem so taking it off cured it.

 

If you can attach the latest .dmp file located within c:\windows\minidump, perhaps I or others here, can analyse the dump file and check to see what is going on.

 

Control Panel - System - Advanced - startup and recovery (settings) - untick the automatic restart box.
That will prevent xp from restarting but will create a report that you can analyse.

 

Thanks for the info, but if you read carefully, the initial poster already unchecked this option.

 

Thanks guys for all the help. About an hour ago i reboot my windows XP and reformatted my hard drive. Before it seemed like it COULD have been my NVIDIA display drivers messing things up because one time in the BSOD my NVIDIA driver showed up. I installed the driver which came with my video card, but my computer still restarted. So then i installed the drivers from the NVIDIA website... still had problems. So yes, as soon as i can configure my computer again (by tonight) i'll post the .dmp file so you guys can check it out. thank you very much.

 

I am unable to attach the latest .dmp file because this thread won't let me. The name of the file is Mini123105-04.dmp I always seem to get this message on the BSOD "IRQ_NOT_LESS_OR_EQUAL" Recently I ran memtest 86 on both of my 512 sticks of ram and on one ram I found a bunch of errors. So now I'm only using the ram that had no errors. However, My computer still restarts, same BSOD at random times. I hope nothing is wrong with my video card or motheroard.....Help.

 

just a shot in the dark, but do you think it could be overheating or dusty inside?
nevermind, i just remembered it's brand new. dust wouldn't be the problem then.
have you run chkdsk, scandisk, defrag and whatnot?
anyway, good luck.

 

no, it's not overheating inside and yes, i've ran those tests. my cpu is at a good 35C. I am thinking there might be something wrong in my BIOS, but I doubt it. I've run into a dead end.