A7V333 - Reboots - Hard Drive Problem?

A7V333 - Reboots - Hard Drive Problem?

I have the following system -

ASUS A7V333 - motherboard
Athlon XP 1800 w/ Thermalright SLK900 heatsink and 92 mm Stealth Fan
Corsair 512 mB XMS2700 (1 stick)
Geforce 3 Ti200 Video Card w/ Zalman HP80 Heatsink
2 200 GB WD SE Hard Drives set up as a 400 gb RAIOD 0 Array
1 60 GB WD SE Hard Drive
1 SOny DVD Burner; 1 PLextor CD Burner; 1 Creative DVD Player
1 ATI TV Wonder VE Tuner
1 Linksys NIC Card
Windows XP Pro w/ SP1

My problem is during normal operation my computer reboots randomly and gives me "System Disk Not Present - Insert boot Disk" error.

I had previoulsy posted a message on this prob when I had the RAID 0 array as the system disk. Since I could not fix the problem I reformatted and installed the OS on the 60 gb Drive. (I had heard that 200 gb drives were not 100% reliable, plus I wanted to see if maybe it was a problem with the RAID Array).

With reboots on the RAID array as the system disk I would get an "Array Offline" message and the system would not boot. Now with the 60 gb I get the "Sys Disk not present" message and the system wont boot.

If I turn the system on and off (not just resetting) it boots up fine nad pick up the system disk. When it boots I run benchmarks on it to see if I can cause a rebbot. I have have no reboots after running benchmarks like Prime95 for 12 hours and 3dmark2001 for over 24 hours without a reboot. Other times after 1 hour it just reboots.

I checked and switched the cables on all of the drive to make sure I did not have a bad cable, but it did not resovle the problem.

Could it be an overheating problem; a bad mobo connection; or just a bad mobo?
Again, I checked all of the connections to the drive and mobo and could not find anything wrong.

Any opinions?

Thanks...