I forgot to mention I also ran the Seagate drive diagnostics (full scan) - came up clean.
Here is the problem. Occasionally, my computer will not boot. When this happens, it appears to be caused by the boot hard drive not being recognized. When this occurs, if I restart it several times, the drive will get recognized and then I can boot to XP Professional SP2. When I am in XP, I can work for a while but then the PC freezes. I can still see the display on the monitor, but everything is completely frozen. I have to reboot. When I reboot, most of the time the boot hard drive isn't recognized and (as mentioned above), I have to reboot several times. Sometimes, I just have to let it sit over night.
I originally thought it could be a heat issue. However, it happens on a fresh boot after sitting all day.
Here are some specs:
- Windows XP Pro SP2
- 2 Seagate SATA drives (< 2 years old) - No Raid, just connected via SATA
- 1.5 gigs of DDR RAM
What I have done:
- Ran Windows Defender - came up clean
- Ran AVG Antivirus scan - came up clean
- Recently reformatted boot drive

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic