Though I am unfamiliar with your scenario, perhaps you could post a typical list definition configuration (of a list that causes a problem).  We might view a keyword that might confound things.

/Pete

 At 18:24 6/19/2006 Monday, Bulterman, Henri R. wrote:
>These days MITRE uses Exchange for mail and calendars.  Our list server
>We know that there is a problem with the Outlook calendar and the lists
>on the list server:  Users can apparently send an invitation to a list
>on the list server, and that works OK, but if they then update the
>meeting things get a bit messed up, with duplicate meetings scheduled.