When you attempt to remove Plus! you receive a message similar to:
1635 This patch package could not be opened. Verify that the patch package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer patch package.
You have a corrupt registry key.
to fix the problem:
01. Use the Registry Editor to delete the following key:
02. Start / Control Panel / Add or Remove Programs.
03. Select Microsoft Plus! for Windows XP and press Remove.
04. When prompted, press Yes to confirm.
05. Shutdown and restart Windows XP.
06. To re-install Plus!, insert the Plus! for Windows XP CD-ROM, holding down the SHIFT key to prevent it from auto-starting.
07. Start / Control Panel / Add or Remove Programs.
08. Press Add New Programs, in the left-hand pane.
09. In the right-hand pane, press CD or Floppy.
10. Follow the on-screen instructs to complete the installation.