I have a user who cannot connect to Exchange under there profile name locally. They can still reach OWA. It doesn't matter which machine they go to so I think it is an AD issue. There is a DCOM 10016 event in the system log that may be related: The machine-default permission settings do not grant Local Activation permission for the COM Server application with CLSID {A4199E55-EBB9-49E5-AF1A- 7A5408B2E206} to the user NT AUTHORITY\NETWORK SERVICE SID (S-1-5-20). This security permission can be modified using the Component Services administrative tool. The error when connecting to Exchange in Outlook 2007 is: The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action. Thank you, Leto the just

Starting from the beginning, is outlook in offline mode? You can see this in the bottom-right corner of the window. If it is, click the area and uncheck Work Offline.