The messaging interface has returned an unknown error.

Hi all,

Looking to see if anyone else has had this error and found a way to fix it.?

Windows 7.

Outlook 2003 reports "The messaging interface has returned an unknown error. If the problem persists, restart Outlook."

This happens when I select a recipient via To, CC, or BCC. I can reply OK.

Searching the net I have tried the following, all with no success.

Ran ScanPst repair tool.
Ran Detect & Repair
Ran Repair from Control Panel/Uninstall/Repair. (Probably same as above, but I am struggling here :) )
Renamed the outlook.pst file and used a saved backup renamed to outlook.pst
Created new profile, added one account.
Disabled all Addins, COM and otherwise.
Started Outlook once with /resetfolders

I can get it to work with /safe, but then lose all my templates and the rules all say (for other machine) and do not work. I have a lot of rules. ;)

Also I recently lost my right click options for my messages. Right click works in Calendar.
I have accumulated 15 email accounts over the years and recreating them (if I can remember the passwords, as most are very old) is going to be a pain. :(

Does anyone have any other ideas to try please.?

TIA

The messaging interface has returned an unknown error.