We've had some issues with a user who has upgraded to Outlook 2010 and attached to an internal Exchange 2003 SP2 server. They get errors more or less saying cannot send, contact your administrator and then a long error string whenever attempting to send. They receive just fine - but can't get any outbound flow.

We recreate the users profile on another Windows 7 machine with Outlook 2010 and it worked fine. Concerned this might be an issue that rears it's ugly head later or at some random time. We noted some KB docs about the issue recommending registry changes - we've reviewed and ensure these changes were made and still have the issue on the one machine.

Any thoughts?