I recommandation is change the motherboard
http://blogs.zdnet.com/Berlind/?p=863One section of the article:
most of the users who have finally gotten their problem solved were able to reach a resolution not through a BIOS update, but rather, a motherboard replacement or a new system altogether. Anna responded that her suggested HP BIOS update is a new one that specificially addresses this problem leading me to wonder (regardless of whether it works or not) what took HP so long to address this specific problem. Wrote Anna in a subsequent post:...read the article