Hmmm this might be difficult. Have you tried putting in your windowsXP cd and tried repairing. your master boot record(MBR) or some of the other repair options.

You will need to let it start (boot) the comp. from the cd.

The only other option I can think of is for you to restore your system to a previous point before you d/l the file. This may have some other side effects also with anything you have done after that time.