Comment 8 for bug 870874

I see a similar problem here after upgrading from a working 10.04 setup with nfs mounted home directories and ldap user database and kerberos authentification. Weh using lightdm, the systems seems to hang. When starting gdm, the login is taking place but the gnome/unity sessions are not started. When the user is logged in on the console (Alt + F1 etc.) and sets the display variable correctly, it is possible to start gnome-session manually.