Entourage 2004 Calendar not syncing with Exchange 2003

Greetings!!! I have a user that about 3 months ago start having issues with Entourage 2004 not syncing his calendar with Exchange 2003. He is running OS Tiger and Entourage is version 11.4.0. I have done some looking online but really could not find too much in regaurds to this - some users pointed to calendar corruption or the likes of that. We are planning an upgrade to take place but right now I need to get his Calendar to sync with Exchange. If anyone has any suggestions that would be great.

Thanks!