All thru kde4.0 to 4.2.0 (inital release) kdm worked  but after updating
from the openSuse repo kdm does not function. The kdm login
screen shows, I can select the user and enter the password but after a
few seconds the kdm screen returns (selecting diff. users or de doesn't
help).

Xdm works fine (as does startx) and running kdm from the command line
displays no errors.

Also, the login manager module in systemsettings opens
the kdesu dialog, accepts the password and then nothing appears. Tried
kdm kde3.5.x and the same.

I did post on for openSuse forum but so far no response

thanks,

tail of kdm.log:

X.Org X Server 1.5.2
Release Date: 10 October 2008
X Protocol Version 11, Revision 0
Build Operating System: openSUSE SUSE LINUX
Current Operating System: Linux circus 2.6.27.7-9-default #1 SMP
2008-12-04 18:10:04 +0100 x86
_64
Build Date: 28 January 2009  05:20:44PM

        Before reporting problems, check http://wiki.x.org
        to make sure that you have the latest version.
Module Loader present
Markers: (--) probed, (**) from config file, (==) default setting,
        (++) from command line, (!!) notice, (II) informational,
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Thu Jan 29 10:50:33 2009
(==) Using config file: "/etc/X11/xorg.conf"
(EE) Failed to load module "type1" (module does not exist, 0)
Could not init font path element /usr/share/fonts/TTF/, removing from
list!
Could not init font path element /usr/share/fonts/OTF, removing from
list!
Driver not XRANDR 1.2 capable, ignoring DISPLAYMANAGER_RANDR_MODE_*
settings

Are you using autologin? If so, try disabling it.
EDIT: Nevermind, I misread.

Given the severity of the problem ( assuming you are not running KDE:KDE4:UNSTABLE ) the problem will have been fixed. If it is not and you are using KDE:KDE4:Factory, you might want to ask the repository maintainers about the problem.

[resolved] - problem was pam related - somehow a file in /etc/pam.d after an upgraded had a line requiring resmgr.so which is no longer provided with the current version of openSuse.