Master/detail = Stack Overflow - Help!

I have a D2 application accessing Paradox tables.

Whenever I setup a master/detail relationship between tables and create
a form to display this data, any attempt to post data causes a stack
overflow. The setup of the database is about as standard as you can get
for a Delphi/BDE app - so does anyone have any ideas why this may be
happening?

TIA
--
Jeremy Collins