I can also add that I am running the same application on another server who handles 40 mailboxes, and I experience the same.

Hi Dan,

Where are those errors occuring?  In th Windows Application Event log?  A pop-up on screen? 

Do they only occur when SMSMSE is attempting to scan a particular message, mailbox, etc?

Also, please be sure to include the exact version of SMSMSE that you are running.... with these additional details, the forum might be able to identify similar circumstances that have happened before.  Alternately, of course, you may find that Symantec Tech Support can provide a quick solution.

Thanks and best regards,

Mick

Hi.
It is a popup message from Symantec.
The message occurs when SMSMSE try to scan automatically our mailboxes according to schedule. Or when I try to scan manually.
I run version 6.0.9.286
I guess its on different mailboxes the application stops each time.

Try clearing out the AD cache files. You will need to stop the SMSMSE services and then go to the SMSMSE directory in Program Files. Inside SMSMSE you will find the version and theninside that a Server folder. Inside that you need to go into Config and delete all .mb and .pf files.

Then start the service back up. After a few minutes SMSMSE will cache your Active Directory again and have a fresh user list. Then try running the scan.