>Its a conspiracy I tells ya!

You mean the line in the source code saying "If Creator = 'Geoff Worboys'
then CreateTrouble"?

>Has anyone got any useful ideas or suggestions on how I might try to
>isolate the problem?

Knowing you are one of the real guru's of Interbase/IBO, I'll have to say
probably not to the 'useful' bit, but I've got plenty of ideas...

>This is one of the simplest tables in the database,

Good.

>it has a primary key and only one foreign key. No computed columns or other
>complexities.

Try dropping the foreign key and see if your error persists.

a) If it does, I guess the error has to do with your table. Drop the table
and try to recreate it. If it still persists try finding what's the
difference from the other tables (character set, fields, field names etc.)
and create new tables with the same characteristics. E.g. create another
table with the same 19 Int64 fields. If nothing else works, try creating
the tables of your database in a different order, to see if the problem
moves to another table.

b)If the error disappears, check if you've exceeded some limit (when Geoff
says big, it means HUGE). Delete foreign keys from other tables, to see if
it just was one to many foreign keys for gbak, and check for other things
coming to your brilliant mind ;o)

Don't know if any of my suggestions is of any use, but I guess they'll at
least make you dig a bit further.

Good luck,
Set