As said partially in the title, here are the specs from this computer. It is a home-built computer, which has been working perfectly for two years.
Gigabyte P4 Titan Motherboard (model: GA-8VM800M)
512 mb RAM
Windows XP Pro
(1) 120 GB Ultra ATA HDD
ATX Power Supply (350 watts?) <-- not sure yet <--
The problems all started when the computer would not even power on. After extensive testing and tinkering, we determined (2 computer guys) that the motherboard was bad. So we replaced (for the above mentioned). Then the computer would power on. All kinds of error messages were coming up and it would bluescreen or simply lock up. In order to rule out viruses, we reformatted the hard drive and reinstalled Windows, ran the updates, reinstalled anti-virus, etc. When we began to reinstall the programs the computer began acting even more erratic...it would power off with NO error messages; just like it was unplugged. Note, that we are able to monitor when the computer shuts down the CPU usuage spikes way up.
I'm not farmiliar with this problem and I know there could be many possibilities. Any common problems like this? Also, what is the best place to start.
I know that this may not be enough information for a complete analysis, but if any of you have had similar prolems, please let me know.
If you need more information, please let me know specifically and I will find out ASAP. I really appreciate all of your suggestions!! :-D