I am using Ubuntu 12.10 with gnome 3.6. It was working fine. But now after I installed some updates of gnome, I am unable to successfully login into Ubuntu. The Ubuntu boots up normally and after loading the wallpaper it hangs up. Nothing else is shown in the desktop. Alt+F2 doesn't work. Ctrl+Alt+F2 is working.
How can I resolve this problem? Is it possible to login into Unity desktop, if gnome has caused this problem?