Billnc,
as technical said, check the bios settings first to make sure all is well.
Then these steps might help (from HP support)
Disconnect all peripherals and internal non preinstalled devices from the PC, except the monitor, keyboard, and mouse.
Turn on the computer.
When the initial blue HP screen appears, press the F10 key repeatedly until a recovery menu appears. The progress indicator that first appears does not indicate that a recovery is taking place. The progress indicator represents the time before the recovery process is started.
When the Recovery screen appears, click Next, and then click Yes to perform a normal, non-destructive recovery.
To perform a destructive recovery, click Advanced, and then click Yes.
CAUTION: A destructive recovery will format the hard drive. This will delete all the information on the hard drive and reinstall Windows and the original software that came with the computer.
After the System Recovery is complete, the computer restarts and continues into Windows setup. Complete the setup screens and wait until the computer finishes the setup.
NOTE: It may take a long time to complete Windows setup. This time varies and may take over an hour, depending on the amount of files that were stored in the user account folders (Like My Documents and the Desktop).
This link might help if it's a bios problem
http://h18000.www1.hp.com/support/files/deskpro/us/locate/7_404.html#0