Could be worse. The only time I've seen anything like this was on my dads machine. He first tried an Epox board, and it had random boot issue similar to what you're describing. Just before the return policy ended, he sent it back for a DFI board. No problems. If I had to guess I would guess that it was a problem with the IDE controller. That or an odd incompatibility between the drive and the mobo. Either way a new $120+ mobo was the fix. Drives are cheap.
ya, lucky me, good thing i had a spare 300gb lyin around, still in Godly condition