Hi Paul,
Even though some have had success in changing DataSessions, I advocate against it. I reccommend only using SET DATASESSION TO in debugging. From VFP Help--"SET DATASESSION is typically used to debug forms, and should not be issued when a form is active."
You have just encountering one of the reasons. Combos are another. Ditto for refreshing bound controls.
You can have lots of private datasessions. Just don't try to use the cursors from them all in the same form.