dialog reports X server already running on display 0

["Robert Harrison" <robstar anotherdimension net>]

Hi folks,

I hope someone can help. I'm running debian sid/unstable with gdm
2.4.1.7-1 installed. I've got a single local X server set up to run on
vt7. When logging out of a KDE or Gnome session I often get a text dialog
reporting the following:

"There already appears to be an X server running on display :0.  Should I
try another display number?  If you answer no, I will attempt to start the
server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a
function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually
run on consoles 7
and higher.)"

Selecting 'no' always results in the server restarting correctly and the
gnome login screen being displayed, however I was wondering why the dialog
gets displayed?

The gdm log file reports:
Fatal server error:
Server is already active for display 0
        If this server is no longer running, remove /tmp/.X0-lock
        and start again.

It's almost as if a race condition is occurring, i.e. gdm is launching a
new X server (AlwaysRestartServer=true) before the old server has fully
shutdown. I've set the server to be handled, but I'm wondering if I'm
missing something in the configuration?

Any help appreciated,
Rob.