Thank you Dimitry and Ann for your responses.

It must be something that is going wrong with the backup of the
database. I normally make use of the freeware utility Firebird SQL
Database Manager which can be found over here:
http://www.crypton.co.uk/freetools.html

I am quite sure that this tool (UI) must make use of GBAK.

When on the Live database, I can "select *" the particular table, and I
can also "pump" all the data from that table to another database with
the same table structure, using IBPump, without any problems. This
makes me think that the problem must be with the backup process itself,
when making use of the free utility mentioned above.

I have now executed a manual backup making use of the GBAK utility
directly, and restored this backup successfully.

Interesting one.

Regards
Marius