Why do I receive the error message "Setup can not uninstall Windows XP because the necessary registration information is missing" when I try to uninstall XP?

A. You might encounter this error message when you attempt to use the c:windowssystem32osuninst.exe command and either of the following conditions exists on your computer:

The Undo folder is typically located at the root of the C: drive and contains hidden and system attributes. To view the folder from the recovery console or command prompt, you need to type

dir /ahs

or set the folder permissions by typing

attrib -sh c:undo

If the folder is missing, you can't uninstall the OS.

If the registry information is missing, try restoring a previous registry backup. Again, if this information is missing, you won't be able to uninstall the OS.