Outlook 2003 Manually Disable Addins
In Outlook 2003, some "Addins" are not shown when digging through the Tools menu. If you need to disable a corrupt Outlook addin that does not show within Outlook's windows, you have to get to those addins from the registry.
1. Run regedit. Type the "regedit" command from the Start menu search bar (Windows Vista or 7) or from RUN box (Windows XP).
2. Navigate to “HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Outlook\Addins”.
3. View the available subkeys of the Addins folder. These are addmins installed in Outlook.
4. Set the specific key to “LoadBehavior” of 2 in order to disable that corresponding addin.