Login issues

I’m having a couple of problems with login managers.
I installed from the kde4 livecd but decided I wasn’t keen so installed gnome.
I’m now using gnome with the kdm4 login manager.
I’ve set the options for all users to shutdown in yast’s /etc/sysconfig editor but when I try to reboot or shutdown it just dumps me at the login screen.
If I switch to gdm then I can shutdown ok but each time I boot up my wallpaper keeps being changed to the login one.