|Which file is missing? You might manage to repair the missing file from Win XP CD recovery console, assuming that the rest of the installation is intact.|
Alternatively, you can try to perform a repair installation which would replace all system files, including the corrupted ones.
Post back the name of the missing file OR try to perform a repair installation.
Boot from the Win XP CD and follow the instructions on the website linked below.
Google is your friend
Have a GREAT day!