Windows 2000 comes with Internet Explorer 5.01.
If you upgrade Internet Explorer, and subsequently install a Service Pack with the option to save the service pack uninstall information, the service pack install removes the Internet Explorer uninstall registry entry.
To workaround this issue:
1. Uninstall the service pack.
2. Remove Internet Explorer from Add/Remove Programs.
3. Reinstall the service pack.
If you cannot remove the service pack, or if the option to remove Internet Explorer does not appear in Add/Remove Programs:
1. perform an in-place upgrade of Windows 2000.
2. Install the latest service pack, without the back up option.
3. Install the latest version of Internet Explorer.