Try running Office Diagnostics.

--
Milly Staples [MVP - Outlook]

Post all replies to the group to keep the discussion intact.

After furious head scratching, DeniseV-WA asked:

| I just installed Outlook 2007 with Business Contact Manager. My old
| version was 2007 but did not have BCM. When I try to edit a
| contact's info, I get the message "The messaging interface has
| returned an unknown error. If the problem persists, restart
| Outlook." It won't let me save any changes to my contacts. HELP!!!
|
| Did Outlook not install properly? What could be the problem?