I am having problems with my computer restarting out of nowhere. Sometimes when it restarts, it goes all the way through but sometimes it gets stuck and doesn't restart but the power light is still on. I just recently took it in to get repaired and they put in a new power supply. Everything was working until that happened. Afterwards, it started with the random reboots/shutdown. Sometimes it would last for 5 minutes before it reboot and sometimes after about 4 hours, it would reboot so its random. Could anyone possibly tell me what could cause this. I sent my computer back to the shop to check and they said it ran for them the whole time it was there. Keep in mind I only brought the box/harddrive part of the computer (the main thing). No other cables or parts.

Other info

I checked for dust and cleaned
I also switched outlets to see if it was the outlets
I ran my antivirus and nothing was there

AMD Athlon(tm) XP 3000+
2.16 ghz, 448 MB of RAM

Memory in use 53%
Total Memory 458096 KB
Available Memory 214116 KB

Mainboard Asustek computer A7N8X-LA
BIOS American megatrends (2/24/04)

Austin Power Supply
Model: DR-83203TX
(upgrade from DR-B300ATX)

I also checked system errors and I get these

Tcpip
Dcom
Service control manager

Just now I got the blue screen and it said something about checking disk space, and I done that. Alsoit said something about may need bios update.

Random reboots are annoying because you can easily lose what you're working on at the time. Random reboots are difficult to diagnose, because there are many possible causes.

what OS are you on? If you are not already on it, I would upgrade to windows XP. This alone sometimes can stop the restarts.

while hardware can cause it,

software can be a huge cause. Have you recently added any new programs? Or updated any programs?

Random reboots are annoying because you can easily lose what you're working on at the time. Random reboots are difficult to diagnose, because there are many possible causes.

what OS are you on? if you are not already on it, i would upgrade to windows XP. this alone sometimes can stop the restarts.

while hardware can cause it,

software can be a huge cause. have you recently added any new programs? or updated any programs?

I'm using windows xp and I just got a new power supply. It didn't start happening until then. When I got my computer fixed, the guy installed malwarebytes but that is the only program he put on there other than the power supply. This is when it started happening.

That happened to me before after getitng a new power supply. Eventually the power just stopped coming on all together. I would take it back to the store you got it from and have it tested on another computer. Or test it on another computer if you have another one available.

But first try removing the malwarebytes. It could be corrupted somehow, and if that's the problem, that would be a much easier fix than trying to fix or replace the power supply

I am sure the shop stands by it statement of it being on whole time at shop, but if issue has only started since the supply was changed.

Was that the reason you took it to the shop, power supply?

Check and make sure that the fans are still spinning when turned on.

Would have to go with what caused the issue to happen, the power supply being changed