Ken,
I'll toss in here a little pearl I put in the PTF-OOP book.
Problems that go away by themselves can come back by themselves. *s*
The point being you really should try to determine the underlying root cause of the problem was and what changes where made to cause the change in behavior if you want to keep from having to chase this down again sometime in the future.
>Many thanks for your contributions gentlemen. I have been told by one of my team that this issue 'resolved itself' after the combobox was deleted and rebuilt from the component palette.