Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Check the below links which describes about the same issue
http://social.technet.microsoft.com/Forums/en/outlook/thread/ec85d209-aa1e-4a34-8d85-bf442e9524cb
Note: The above links also apply to Outlook 2007
Sachin Shetty