Dell CERC SATA
RAID 5
3 x 80 gig SATA
Onboard video/Network
Additional Netgear NIC
Tape Drive.
2 gigs RAM
single Processor on Dual processor board.
Small Business Server 2003 Standard SP1

Server randomly reboots. It gives no BSOD. It shows no errors in the logs at the time or just before the reboot.

So far I have.
Run Dell diagnostic Utility. Found no errors.
Ran RAID utility to verify each disc. Disc 0 FAILED. Replaced harddrive and resyncd RAID. Reran verification. All drives Pass.
Still reboots randomly.

Ran chkdsk /f/r
no bad sectors

Uninstalled Symantec AV
Reran dell extended diagnostic. No errors.

Ran Memtest for 7 hours. No errors.

Manually checked vendor websites for updated drivers. All were up to date except the RAID storage manager but I think that was a software and not driver update.

Ran Hmonitor . No overheating issues.

Cleaned the small amount of dust from the case.

Reseated RAM.

After reboot there is NO indication that anything bad happened other than the standard "I was shut down badly, why?" dialog box when logging back in.

starting to make me a little crazy.

any ideas?