Outlook contact record minimising when another user closes a contact

[pcomms]

Not sure whether this is best posted here or on Microsoft Exchange so will do both.

We are running Server 2003 with Exchange Server.
Within Outlook, when user 1 has an email or a contact open and then another user closes any contact, user 1's email or contact is minimised without warning.

All users on XP Pr, Office 2007 although same happened on previous versions of Office.

Help, its driving me mad....again

Thanks