If this happens to be an AMD processor C700, the motherboard seems to have some problems that manifest in various ways similar to the symptoms posted. I can't seem to find the thread at the moment but the problem is related to the onboard graphics hardware. As it progresses, the laptop will fail to powerup at all. There are people making repairs to these for a nominal fee: http://www.ebay.com/itm/Compaq-Presario-F700-C700-C300-V2000-CQ70-Repair-Ticket-/220692486120?pt=LH_DefaultDomain_0&hash=item33624c17e8
I am not recommending this service, just mentioning for reported troubles. Read the description for the service and it will be clear that something more than software could be the problem.