Its most definitely NOT software, its the southbridge chip! Look on your local craigslist and find a decent tech doing reflows, you shouldnt have to pay more than 100 bucks for a tech with the proper equipment to do a reflow out of his house, i pay 80 here in rochester, ny. In the process, if the tech does any copper heatsink modifications, have him do that as well to keep from having this problem in the future. HP is crap, they run far too hot, the southbridge chip on this model de-solders itself from the board. Ive bought 3 of these models with the exact same diagnosis for dirt cheap, had them reflowed and they are in perfect running condition for re-sale.
AGAIN... its not software as everyones suspects, its hardware, have the southbridge chip reflowed!