Just thought I would start this thread with tips we all live by.
My first one will be about the dreaded CDO.DLL And Mapi32.dll problems.
The previous admin here installed and attempted to activate bes, but left with it half activated, when I started, new clients on the BES were unable to accept meeting invitations and thats where my CDO/Mapi32 problems started...
If fought this for a week, searching forums and google, until i found out that the bes versions of these DLL's had to be as new or newer then the version on the exchange server.
I quickly installed Exchange SP2 directly to my BES server and it immediatly fixed my issues for all clients...
So my tip for everyone is to keep your BES at least as updated if not more updated then your exchange server.