To begin troubleshooting, I'd recommend the following:
1. Clear the event log in BIOS and load its default settings.
2. Test with the most current BIOS.
Note: If your board's an Intel, please, make sure you refer to the following stie:
I have the most current bios 1307 from ASUS. It didn't matter. But it's now a mute point as I had a NB/SB chipset failure last week. I'm starting to wonder i fthat was the root of all my problems. As my system is liquid cooled and the temps were between 65-80 C. ASUS RMA'd the board, so I'll let you know.