1. OS-Windows XP Home
2. Slowed, froze, blue screened.
3. Select startup, F8. Nothing worked.
4. Formatted hard drive with wipe (format disk).
5. Tried to install XP Pro.
6. Power shut off at end of loading startup files.
7. Retried several times. Finally, loaded XP Pro.
8. While loading Office, froze, blue-screened.
9. Started over, but this time with original XP Home.
10. Power continues to shut off after loading "checking system and loading startup files".
11. No battery inserted.
12. Direct power.
13. When power goes off, unplug power supply, plug back in to be able to start again.
14. Is something in the startup files triggering the power shut off?
15. Is this a software or hardware problem, or both?

Did the computer turn off whilst installing XP?
Perhaps there is a problem with the hard drive. Did you reinstall XP because of being unable to boot up?
Can you tell us what the BSOD error is?

There's no need to number each line.

Please refer to info above with the numbers. There was no error shown. The power shut off while trying to load XP Pro and Home. Thanks if you can help!

their is a difference between loading and installing. What I am asking is does the PC turn off whilst you are installing from CD Or after the installation begins from the hard drive?

Try a linux live CD to see if there is something wrong with your HDD or if it is something else. If you can boot from the CD then it could be something else other than the hard drive. If the CD works and the PC doesn't shut off it could be a fault with the hard drive.

What is a linux live CD? It actually cuts off from the CD. The HD is formatted.

If it cuts out whilst using the CD then It probably is not just the HDD.

Is this a laptop or desktop?

Number 13. in you original post, Does it refuse to start if you don't unplug it first?

Is there anyone out there who actually has worked on an HP Compaq Presario 2100 with similar problems? I really need to discuss this with them.