Is there a way to force a reinstall an drop all mnesia config tables?

Hi,

Last week I installed an ejabberd server on ubuntu 10.04 server with aptitude.
Everything was fine until, without knowing, I changed the hostname.

Now ejabberd is not starting up, I tried with all hostnames, tried with /etc/default/ejabberd but nothing seems to work.

I removed ejabberd and erlang, (apt-get purge and autoremove) then reinstalled.

I may have changed something else that I don't know.

So, I think that if I make a reinstall and somehow get ride from all the old configuration, it may work.

Any suggestion?

Thanks a lot!