MS Exchange - Retrieving Data?

[Kerplunk]

I have recently installed a new MS Exchange mail server, upgraded spec from the old one, I have copied everything across and all is working fine, but, whenever I turned the old one off and the new one was running 'alone' some when you click on some emails a message box pops up saying "outlook is retrieving data from <Server name>" and crashes.

Basically it seems its trying to retrieve data from the old server, if both servers are on it is fine...but if the old one is turned off its trying to find some data :S

Anyone got any ideas/clues as to what it is trying to find?

Thanks

 

[Kerplunk]

Second server to the same domain, yes. It has replaced the main server. Basically i have added all mailboxes onto the new server from the old one.

 

[Kerplunk]

Thanks guys, just for ref, we are running Outlook 2000 clients. Does that have cached mode?