One of my friends is using Ubuntu 12.10 Unity for some time. And finally he decided to try gnome shell. Hence he installed gnome shell and now while logging into gnome shell (from login screen) this weird thing occurs. Its falling back to old gnome. Tried restarting the laptop but still didnt work. He has Nvidia Gforce GT 540M graphic card. Didnt install any proprietary drivers. Tried disabling the graphic card in BIOS as well. Please help.