I don't get the problem reproduced in a smaller sample app. We moved
some code back and forth here and the problem has gone. It seems the
issue is somehow when a combobox is bound to a datasource in a panel
or frame and that datasource points to a query in another frame or
panel.
Sorry, I'm running out of time (deadline Monday). Glad it works now,
but I will try to make a demo app when I have more time.

Mirco