Oct 23, 2006 09:59 PM|jasonjoh|LINK
The event log indicates that the thread that is trying to execute inside the System Attendant which is responsible for creating public folders for your OAL's is "blocked." This is usually due to misconfigured backup software taking the public folder store
offline or otherwise making it unreachable via MAPI.
The System Attendant does a lot of work to OAB's during Exchange's normal maintenance period, which is usually between 1 AM and 5 AM every night. If you've got backups running in that same period, try changing the schedule of your backup to happen afterwards.
If that fixes it, then you can take a closer look at your backup software's settings if you wish to have it run at the same time as your nightly maintenance.