I can only suggest what i would try. I don't know what the problem is and i'm only offering advice, hopefully it will be good advice.
The first thing i'd try is to look for any bios updates for my motherboard, and checking to see if there's any compatiblity issues there. If no updates are available, i'd reset my bios back to defaults. You should have your documentation handy for this to locate the appropriate jumper and follow those instructions.
I'd remove all extra hardware that wasn't necessary for initial installation like extra CDRoms, modem, ethernet card, sound card, etc.
I would get my hard drive's manufacture set-up utility and use it to partition and format my drive.
I would make sure my hard drive was on it's own IDE channel, with no slave drive attached (making sure it was jumpered correctly).
If ECC was enabled in my Bios, i'd disable it, along with virus checking (I think the normal defaults are disabled anyway).
I'd disable USB support and onboard sound in my bios.
Those are the things i can think of right now, if i can think of anything else i'll edit my post here. Good luck man, i really hope you can get it working.