Try with a new mail profile.

--�
Milly Staples [MVP - Outlook]

Post all replies to the group to keep the discussion intact. All
unsolicited mail sent to my personal account will be deleted without
reading.

After furious head scratching, moshken asked:

| I am using the new beta 7, and I can't make any new appointment. I
| get an error message "The messaging interface has returned un unknow
| error. If the problem persists, restart outlook"
|
| I did reinstall the outlook and still I have the problem.
|
| I appreciate your help.
|
| Thanks :-)