I have many users with Exchange Activesync working perfectly fine and this one user can get his email/contacts/tasks but his calendar does not sync correctly at all. It seems to sync a few old "ghost" appointments that aren't even on his calendar and a few current ones.
I have tried removing the account, rebooting the phone, adding the account back etc. I also tried adding this account on my iPhone and the same thing happened. To rule out the iPhone, I setup his account on Windows Mobile 6.1 Emulator and the same issue occured. Leads me to believe it is an Exchange issue but don't know where to look at this point (his mailbox/AD settings seem to be pretty standard)
We are on Exchange 2003 Standard SP2 (latest patches)