Well... it's an overheating SOUTHBRIDGE. You just need to add a $3 fan to it. Problem solved.
Done lots of times
EDIT: It is a known problem on some HP motherboards, usually AM2+ dating 2-3 years ago. Also 1-2 years old AM3+ ASRock motherboards.
Also saw it happening on some 775 mobos.
I was gonna say, it's GOTTA be an HP. JUST because it's a piece of shit that failed in two years.