To resolve the issue I suggest you to reset the bios.
1. Restart the notebook.
2. When the HP logo appears, press F10 to enter BIOS Setup.
3. Using the arrow keys navigate to exit menu and then select Load Setup Defaults. Then Select Exit saving changes.
After resetting BIOS Perform OS repair:
To repair the operating system without destroying any personal data, use the Windows operating system CD that was shipped with your HP Pavilion
notebook.
1. Ensure that the CD-ROM is connected to the notebook.
2. Turn on the notebook.
3. Immediately insert the operating system CD into the CD drive. 4. Press and hold the Power button for 5 seconds to turn off the
notebook.
5. Press the Power button again to start the notebook.
6. Press any key to boot from the CD, when prompted. The Welcome to
Setup screen is displayed.
7. Press ENTER to continue (Please, do not press R key in this steps).
A
Licensing Agreement screen is displayed.
8. Press F8 to accept the agreement and continue. The Setup window is
displayed.
9. Press R to repair the selected Windows installation.
The repair process may take several minutes to complete. Your Notebook
will restart into Windows after the process is complete.
You can refer the following web site which has the above information in
pictorial format:
http://www.windowsreinstall.com/winxppro/installxpcdrepair/indexfullpage.htmNote: OS Repair steps are same for Windows XP Home and Windows XP Pro.
This should resolve the issue. If you need any further assistance or
clarifications, please do not hesitate to reply to this mail. We would