My team is having the same issue with three MACs. We did not have this issue prior to loading SP1. I have only found this other report here. I find it difficult to believe I have a server issue becasue it did not do this before the SP was loaded. Now I'll have to back it out to get productivity back.
Ever since I applied SP1 to Microsoft Office for Mac 2011, I can no longer access my one Exchange account in Outlook for Mac. The program asks me to enter my ID and password but after I enter them, it again comes up with the request for ID and password. I verified those by creating a PC Outlook account and all worked as it should.

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