Perhaps a new corner of this has surfaced.

Unwittingly (or should that be "witlesly"?) I put
a text box on a form in this heirarchy who's valid
*always* returned false, ie never validating, and
I got a similar error!

Could it be that if, for some obscure reason, an
object in a heirarchy refused to be destroyed VFP
just blithely carries on removing the rest if it,
including the parent object???

Hmmm
Mark