AndyT_uk, i don't have any solutions to submit, but i have a calendar sync issue too and i'm working on it since a long time.
I have a question concerning mapi32.dll, Exchange 2003 SP2 and BES versions are not the same (Exchange version 6.5.7638.1 - BES 6.5.7888.0). I have installed ExchangeMapiCdo.EXE on my BES to have mapi32.dll.
How can i do to have the same one that the exchange server?
Thanks for your help