4.5, I did suspect blackberry as the reason but it happens for non blackberry
users and mailboxes as well. Some of the Execs though are admins for both
Blackberry and Non Blackberry users. The only common factor is the admins
themselves

I just got out of a meeting discussing this very problem!

We have been on Exchange since 5.5 in 1997, now on Exchange 2003, and
this has always been a problem. The only constant that I can figure is
that it happens to recurring meetings that have been modified. (It
happens more often to delegated calendars, but not exclusively. It is
probably that those folks who have the luxury of delegating their
calendar spend a lot more time in recurring meetings. Also, this was a
pre-BlackBerry problem, and in any event I only have 20 BB users out of
about 2000 total accounts.

I've never gotten MS to directly admit that this problem exists, but
it obviously does, as evidenced by posts like this. However, in this
QDoc (http://support.microsoft.com/kb/899704/en-us) discussing calendar
problems, including missing meetings, MS basically says that the only
safe way to modify a recurring meeting is to delete it, wait for it to
disappear from all calendars, and re-create it. While this is total BS
from an operational perspective, from a technical perspective they may
be right.

This bug has been around for at least nine years. MS should fix it -
their workaround is the height of bogosity.