You should have a System Restore CD, or Windows XP CD. Put it in the
CD tray, and restart the computer. Follow instructions, selecting
"Reinstall OS" or similar.
If the restart does not run the CD program, you will have to change
your boot order to boot from CD before boot from hard drive. This is
done from bios setup, which also is accessed from restarting the
computer.
Cheers,
Chuck
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