Entourage synch with Exchange Server

[Emile.Casanova]

I'm a network administrator for a small company that recently got two
Macs which were setup with Entourage to connect to my Exchange Server.
It worked for the longest but now is acting up. Once the user is
working on her PC she has no problem sending/receiving emails or even
looking at past emails.

Once user is on her Mac and using Entourage, the Exchange done synch
and emails gets lost.
Can someone guide me in the right direction on how to fix the problem?

Thanks