John, Milan

I *believe* I have finally got the answer.

Milan, you were right the loopback i/f was not fully running, or was
not running as I would have expected it to.

It turns out that I had a typo in the hostname : my machine is called
quaddra (all lowercase) in the /etc/hosts and it's hostname was
Quaddra (uppercase Q)

Because I have several network configuration I simply save and copy
the relevant files and do a service network restart, one of the
configuration files at a faulty Hostname....

I just wish that the firbird.log file was a tad more explicit!

Thanks a lot to both of you helping pointing me in the right direction.

Didier