I am not a suse user and also more of a startx kind of guy (no kdm login screen), but let me suggest something. Try Deleting all kde related files from /tmp and then login again. Perhaps your previous kde session crashed or something? temporary files were left behind in /tmp? As far as I know the "startkde" script should take care of it, but give it a try.
If you are sure that there are no useful files in /tmp, do a "\rm -rf kde*" in /tmp
(make sure you are in /tmp!!!!!!!!! and safer if you are not root).
Also check your ~/.kde or ~/.kde3, whatever.