The Display Manager was missing (gdm3), I installed it and the login works fine.
Now when I log in there is a blue screen and the cursor, nothing else is displayed.
Is there a problem with GNOME?
Probably.
You might try reinstalling Gnome; "aptitude reinstall task-gnome-desktop" might do it.
Or you might try creating and logging in as a different user, to see if that user has the same problem.
Or you might try selecting a different desktop/WM; "aptitude install xfce4" might do it, and selecting that environment on login.
--
Kent