Troubleshooting

Prompt when you Open

If a previously "installed" add-in is moved or deleted, the next time you close and re-open Excel you will see the following prompt.
If an add-in was ticked and then becomes unavailable you will see the following prompt when you open Excel.
This prompt displays the folder path and the filename of the add-in that cannot be found.

This message will appear every time you open Excel until you remove this add-in from your list.

Prompt when you Select

If an add-in that was not ticked becomes unavailable there is no prompt when you open Excel.
The only time you will see a prompt is if you click on this entry in the Add-ins dialog box.
Selecting it in the list will display the following prompt.

Pressing Yes will remove the add-in from the Add-ins dialog box list and remove the corresponding registry entry.

Disabled Items

The disabled items are stored in registry:

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Word\Resiliency\DisabledItems 

Excel 7.0 Add-ins

If you attempt to view a project in the Project Explorer window it may display a message saying "Project is Unviewable".

This happens when the Excel add-in has been created in either Excel 5.0 or Excel 7.0.
You cannot view or edit the code in these add-ins.