> Bump...
> this error has occurred twice now in 5 days with the intervening days not
> presenting the error.
> I have tracked it down this time to one blob field (value) in this table
> which is a simple plain text blob, which I updated manually and this fixed
> the backup error.

If you'll get error again, please, make a copy of database and give it to me
for analyse and (probably) bug fixing.

Regards,
Vlad