Entourage stuck and updating message list
If that fails and you have Garage Band, try opening and closing it.
27) Message stuck in Outbox which is causing Entourage to stop responding, forcing a Force Quit. In Entourage 2004, this disables schedules from launching at startup.
More info: Font Management in OS X Tiger and Panther Back to Top 19. The fix is to go to the TCP/IP and enter .196 then on the next line type .196.
Click apply and go back to the Microsoft Mactopia download page and get the update. Click the speaker icon next to them to test your sound setup .
Try deleting this preference file in your User's -- do a verify operation.
If it gives you a clean bill of health, you know you are safe in turning off the background checking.
I've done some corrupt database recovery by Importing an Entourage database into Apple Mail and then going back into Entourage.