Root window manager not working correctly

When I login using the gui login for root, the window manager is not KDE even though I select it in the login dialog. Login as user is OK. If I boot in run level 3, then login and startx in as root, it is OK. Does anyone know where the configuration file is that sets this up? (Suse 7.3) I think it ocurred when I tried the Blackbox window manager, although the window manager in root is something else, not sure which one as I have not looked at them all. Art