HP Pavilion DV2910 not booting and beeps once

My girlfriend has an HP Pavilion DV2910 with Vista Home Premium x32. When she turns on the computer, the keyboard lights turn on and I can hear the fan working, but the screen is completely blank and after a couple seconds it beeps loudly yet briefly. Could anyone tell me what this means and what I can do to fix it?

Hi welcome to the forum. Sorry to hear you're having problems.
Did this just happen one day, or stopped like this during an operation, then returned on re-starting?
I would like you to click on the link below & try this method.

Troubleshooting LED Blink Codes or Beep Codes During Startup or Boot - HP Customer Care (United States - English)
Please post your results. I hope this may help.
Thank you.
T

It was a bad CPU, which I replaced. Now I can't get the computer to boot into Windows, so I tried a Hard Drive self test and got "#01 - 07 Fail". I Googled this and it seems to be a problem with the Motherboard. I am just going to buy her a new computer. Thanks for your help and I apologize for taking so long to reply.

Hi,
Sorry to hear you had further problems!
But happy you finally resolved the issue.
Thank you very much for posting back to us,
Happy Computing.