Here is the process for what is occurring right now:
1. User A creates an appointment in Outlook
2. User B accepts the appointment
3. User A is still looking at the appointment prior to User B accepting it and tried to update it
4. User A gets the error message
What happens is that the original appointment is being viewed in Outlook and a change occurs to this appointment that the user does not see. When the user tries to update the appointment he gets a warning saying that it's been updated. Upon closing the appointment and trying it works, this because after closing and reopening he is now looking at the updated appointment.
This is normal behavour and I find it strange that Microsoft does not know about this seeing as I was on a conference call with MIcrisift reps about this in the past. It's funny to talk to people that don't know howtheir own software works.
This usually occurs in the BB world because when the appointment reaches a BB for the first time the BES tags it with a Reference ID on both the BB and Outlook. This inturn updates the appointment but not to the eye of the user. It's the same thing if someone accepts the meeting, the attendee list updates but may not reflect untilt the appointment is closed.
Recreating BES accounts will not fix this, there is no fix that I am aware of. It's typical behavour of Exchange/Outlook but now you have BES in the mix. Your users will just have to live with having to reopen the appointment, not a big deal.
It's not really a latency issue, it just depends on if a user has that particular appointment open prior to the change being made. That's when the issue happens, if the appointment was closed after sending the original request and then opened later to update it should work fine.
Hope this clarifies things more for you.