> > Unfortunately, this is an old InterBase bug. I'm pretty
> > certain it has been fixed in Firebird 1 but perhaps
> > someone else would confirm.
>
> Confirmed!

After a quick test, I do not see any difference between IB5 and FB1 regarding
locking of external files.
In both versions I have to disconnect all users to unlock the file.

Ivan
http://www.volny.cz/iprenosil/interbase