We recently installed a new Windows Server 2003 Enterprise server with Exchange 2007. This was a migration from Exchange 2003. 2 out of 15 users have received the login screen when opening Outlook locally (all Outlook is 2007) and the username/passwords dont take. The screen keeps looping around and the user cannot get into his email account within Outlook. The first user, we re-created his database files and watched Outlook download everything fresh. Seems to have worked but now we have our second user doing it. Not sure why, but I reset the 2nd users password and re-booted the machine and all was fine. The real quesiton is why the login screen is happening. All users are fine if tested in OWA so we know it is not a username/password issue. Seems to be something more related to the LAN and Server talking? Any ideas?