I installed primarily the KDE version. When it was up and running, I installed
Gnome via YAST2 / software install or delete / patterns / gnome basic system
and gnome desktop environment. No errors.

When I (the user created during install) chose Gnome at the login screen
entering user and password the screen turns black and I get an "x" as mouse
pointer. <alt><F2> and login as root then "init 3" and "init 5" brings me back
to the login screen.

If a different user tries to login with gnome, same happens as described above,
but some 10 or 15 seconds later one will be back to the login screen
automatically.