I had that happen to me one time while using a XXX GTX 9800 1gb i send my asus motherboard back to asus and they said the pciE slot was going bad.
Oh please don't say that!
Would there be a way to test my pciE slot? It would make sence, but god I really hope this isn't the issue!
Also, I've been in safe mode for an hour or so and haven't had any problems. Any reason for this?