I know a few other people have seen this with Firefox and the version
of X11 presently on the 2.0 branch, but I have no idea what the cause
might be.

I just built and installed firefox-gtk2 from pkgsrc on a system that
had had all its old packages cleaned off (in other words, a "fresh"
system -- an upgrade to 2.0 followed by a complete replacement of
pkgsrc).

When I start firefox-gtk2 I get this:

    $ firefox-gtk2
    Xlib: connection to ":0.0" refused by server
    Xlib: XDM authorization key matches an existing client!

    (firefox-bin:371): Gtk-WARNING **: cannot open display:  

I tried this:

    $ export DISPLAY=unix:0
    $ firefox-gtk2
    Xlib: connection to "unix:0.0" refused by server
    Xlib: XDM authorization key matches an existing client!

    (firefox-bin:11111): Gtk-WARNING **: cannot open display:  

And this:

    $ xhost localhost
    localhost being added to access control list
    $ firefox-gtk2
    Xlib: connection to "unix:0.0" refused by server
    Xlib: XDM authorization key matches an existing client!

    (firefox-bin:3132): Gtk-WARNING **: cannot open display:  

And I even tried restarting the X server after removing my .Xauthority
file entirely.  To make Firefox work I have to "xhost +", and obviously
that is an amazingly dangerous thing to do.

I have no idea what's going on here.  Can anyone explain it?  It would
be nice to be able to run a web browser!

-- 
 Thor Lancelot Simon	                                      tls@rek.tjls.com
   But as he knew no bad language, he had called him all the names of common
 objects that he could think of, and had screamed: "You lamp!  You towel!  You
 plate!" and so on.              --Sigmund Freud