You may receive the following error message in Microsoft Office Communicator 2007 R2 on a computer that is running Office Outlook:
There was a problem connecting to Microsoft Office Outlook. The e-mail address used in your default Outlook profile is different from the sign-in address used in Communicator. Change your default Outlook profile to match the sign-in address you are using in Communicator, and then sign out and sign back in to Communicator.
Install the following cumulative update:
2291453 Description of the cumulative update package for Communicator 2007 R2: November 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.