ok i have looked around but cant seem to see anything to this issue. We have deployed 2 more remote sites in addition to our main site. Our main site runs Server 2008 32 bit. Our remote sites run server 2008r2 64 bit. We have two domain controllers on the main site, and one domian controller at each remote site. Remote site A can not replicate to remote site b because the way the network is setup. I dont think this is an issue. Remote sites can replicate back to main site, and main site can replicate to remote sites. Now main site houses a 2003r2 64bit exchange 2007 sp2 box. Clients on main site only(from what we have seen) loose connection to exchange from outlook. It asks for login credentials for one of the 5 boxes (dc1, dc2, dc3, dc4, or exchange). The issue is random,it could go away for a week or 10 min. It doesnt happen to everyone, only a select few. We have flushed clients dns, ip, and rebooted their machines. Like I said above, it may help for 10 min or a week. any Ideas? thanks

First I would upgrade to SP3 UR8 as SP2 isnt supported anymore.As for the prompts, gather info on what the users are doing, I assume it cant be reproduced easily?Might want to take a capture when its prompting using netmon.Make sure all OLK clients are fully up to date?Sukh

Yea it is on my plate to upgrade to sp3... I just did the upgrade to sp2 about 3 months ago. (Im new to the job so I am trying to get everything up to date) The users can be doing something as simple as reading email. or trying to send email. The issue can not be reproduced at anytime. It comes and it goes when it wants. all clients Outlook are up to date.

Hi According to your topology,maybe network issue cause your problem. Do these client desktops connect to same switch ?Terence Yu TechNet Community Support