Entourage 2004 Constantly Synchronizes



I have a user running Entourage 2004 on an iMac running Tiger with the latest OS updates, Office service packs, etc. connected to an Exchange 2003 SP1 server. Entourage is constantly synchronizing to the server. I've checked all items on the Calendar and they have end dates. The user does have a large volume of mail in folders that he's created by subject, etc. He also has a large address book. I've set the Send/Receive schedule at 20 minutes instead of 10. He still gets a spinning wheel at several intervals while trying to work in Entourage.

Any help would be greatly appreciated,