The following error message is displayed when trying to install an ArcGIS Desktop 9.1 Service Pack:
Error: "Product Compliance Check One or more version 18.104.22.168 products"
One of the ArcGIS Desktop registry keys is corrupted.
Warning: The instructions below include making changes to essential parts of your operating system. It is recommended that you backup your operating system and files, including the registry, before proceeding. Consult with a qualified computer systems professional, if necessary. Esri cannot guarantee results from incorrect modifications while following these instructions; therefore, use caution and proceed at your own risk.