Outlook could not install the custom actions

The latest funtime error from Outlook 2007 that has crossed the crash/reboot help desk is this:

Outlook could not install the custom actions. The object could not be found

This tenacious little error message popped up for our long-suffering admin staff every time they tried to open a message or create a new one. As you can imagine, it got irritating very quickly.

It's because of a corrupt Forms cache, which needs to be deleted. The fix runs like this:

1. Close Outlook.
2. Under C:\Documents and Settings find the folder for the user who's experiencing the problem.
3. Make sure under the Tools, Folder Options menu that system files are not hidden.
4. Navigate to \Local Settings\Application Data\Microsoft\FORMS, and delete the file FRMCACHE.DAT.

Then clear out and restart Outlook. You'll get a quick flashing dialog telling you that the form is being regenerated, and everything should be fine.