Michael..! Hello...
Does this mean ISA is behaving and you are connected directly to exchange now...?
Hve you treid using another users mailbox.. Or ideally create a new user and mailbox and use this to sync the on the iPhone. I saw a couple of things about WM6.1 where it wouldnt want to sync with a certain mailbox.. I dont have a solution but at least we could rule that out..?