Have a strange situation not sure of how to stop.

Running Exchange SP2 on SBS 2003. Clients have Outlook 2003 on XP.

When a user create an appointment on their personal calendar and then
invites
the Public Folder calendar. The appointment shows up and all is good.

However this appointment is appearently showing up on other users
personal calendars, either
they open the the appointment and then it is automatically populated on
theirs, or some say that
it will automatically show up on their personal calendar.

Is there a way to stop this behavior?

I do notice that the appoint when opened has the accept / decline
option, but the user is not accepting or delcining, just opening the
appointment.

Thanks for any ideas.

f