I have the same problem with my compaq presario, but with a biostar motherboard (I replaced the original board). Haven't found an answer yet. It's called a "cold boot" issue. If you contact hp online tech support, they may direct you to a newer bios program; first, I would try a different power supply if you have one. Flashing the bios is always risky, and unless the newer bios has fixed your issue, it's a waste of time.