You could also try a Repair/Reinstall of XP MCE. Personal files and software you installed should be ok but always good idea to back up first. You will have to reinstall some Microsoft updates and hotfixes again.
Or you could use PC Restore to reset the drive to the way Dell shipped it. You must back up first because all personal files and software you installed will be gone after PC Restore. And you will have to install the latest XP Service Pack and all updates and hotfixes. Make sure you have your installation CDs and software product keys, eg for MS Office etc., so you can reinstall those after PC Restore.
