Entourage fully updates over and over again

[LadyAmalthea]

Version: 2004
Operating System: Mac OS X 10.5 (Leopard)
Processor: Intel
Email Client: Exchange

I have a weird problem with Entourage. I have an exchange account setup and it is connected and was updating just fine the first time. Then, when it updated all the emails and was showing the last ones I received today it suddenly started updating all over again. This happened four times now and I don't know how to stop it. Every time it is done it is fine for 10 or 15 minutes and then it starts updating again.
Has anyone ever had this problem? I asked my friends who use the same exchange server to send me a screenshot of their settings, but the "advanced" panel looks completely different than mine, even though we use the same version of Entourage. My "advanced" panel says only: Synchronization options
( ) Synchronize all items to server
( ) Synchronize only items in this category
( ) Synchronize all items except those in this category
( ) Don't synchronize items to server

I have tried the first and the last without any different results.

Any help is greatly appreciated.

Thanks,
Amalthea

 

[LadyAmalthea]

Perhaps this wasn't clear in my first post: When I say "updating all over again" I mean that it updates all the emails, beginning in May. The weird thing is that there are emails before May, but it always starts updating in May again. And because I have several hundred emails, it takes about an hour to update them all.

Thanks.