We recently upgraded most of our machines to Windows 2000 Professional. We have a few Windows 98 machines still lingering. Immediately following the rollout of Windows 2000 we have run into a problem with opening Outlook 2000. When users attempt to open Outlook, they are prompted to provide a username, domain, and password. Supplying the their correct information returns a message stating that the logon credentials are incorrect. When attempting to open Outlook as a domain administrator the password authentication does not appear and Outlook opens as it normally would. Has anyone had a similar problem?