Can't run kdm, but gdm is fine

[Andrew Ingram <andrew@uk.clara.net>]

Hi list.

I've installed Sid on a new box at work to replace the old crappy bit of
hardware I used to have. My old box used kdm but when I installed Debian
this time, gdm was the default. No problem I thought! After a while, I
started missing the way that kdm and kde worked together so I did an
apt-get install kdm.

However, when I reboot and kdm is starting, I get dumped to the console.
I noticed in syslog that I have the entries:

Nov 25 08:27:58 localhost kdm: :0[2613]: IO Error in XOpenDisplay
Nov 25 08:27:58 localhost kdm[2542]: Display :0 cannot be opened
Nov 25 08:27:58 localhost kdm[2542]: Unable to fire up local display :0;
disabling.

I have a xinerama setup in case that helps, but the whole thing works
absolutely fine under gdm. Can anyone help me with this?

Thanks,
Andrew