[jeiyuu]

This is a tough one.. Haven't used the stock OEM rom since I first bought the phone.. The only thing I would recommend (which I'm sure you might have already checked) is under Settings->Lock uncheck the "Prompt if device unsued for xxx minutes" box. If not that, did you install any other locking programs that might have conflicted something? (S2U2, iLock, or sonthing else?)