no graphical login

[Robert Epprecht <epprecht@solnet.ch>]

On a debian sid box I have the following problem:
When I try to log in (as ordinary user, not root) with gdm I get:

Xlib: connection to ":0.0" refused by server
Xlib: Protocol not supported by server

I have tried to remove/re-install gdm and also to use kdm, it did not help.

If I stop gdm/kdm and log in as the same user from a console I can do
startx and it works fine. While this would be perfect for me, this box
is used by others and they want *graphical* login ;-)

Any help very much appreciated,
Robert