On 10/5/05, Gavan Fantom <gavan@coolfactor.org> wrote:
> Hiroshi SAKURAI wrote:
> > Hi
> >
> > On 10/5/05, Art Lemasters <develunix@gmail.com> wrote:
> >
> >>   Firefox and thunderbird have been failing to start in new
> >>accounts with an error message like the following.
> >>
> >>   Xlib: connection to ":0.0" refused by server
> >>   Xlib: XDM authorization key matches an existing client!
> >
> >
> > I had the same problem on debian sarge.
> >
> > I think you should do
> >  $ xhost +
> > before launching firefox for the first time after installation.
>
> This is absolutely not a solution, and will leave your X server wide
> open to *anyone*, without authentication.

You are right.
After the initial firefox startup you should do
 $ xhost -
and you will be able to start firefox from now on without problems.