Four beeps pause 4 beep [Solved]

Had a HP DC5100 do the same thing. Power Supply was bad
Change it out with another DC5100 and the machine work. Put the bad one in the another machine and the
problem duplicated.
Hope this helped.

My son just had the same problem. I had him clean the dust off the processor heat sink.

I then had him pull one memory stick and then startup, it did. I then had him install the memory stick, and pull the other one. The computer started up fine. I then had him reseat the second memory stick and restart the computer. The computer is now running fine.

Evidently, the memory needed to be reseated.

Same Deal, dropped my computer and it was running terribly, couldn't run any applications so i thought it was dead. Got bored on the phone one afternoon with Rogers fixing an invoice issue so i took off the back panels and started looking around, unseated every component i could and reseated it, now the computer runs better then ever on only half the ram. I'll wait till i'm done cleaning everything out and then i'll reinstall the other GB. Don't worry about the 'Beware' or 'Warranty Void' stuff, just takes a bit of a can-do attitude and a small screwdriver and you can fix it yourself.