I was using ubuntu 12.04 perfectly im my desktop until last kernel update (3.2.0-51). After the update proccess and reboot the system, the unity inteface didn' t start. The only way to login in the system is by tty. I have tried the last kernel versions available in the computer, but I can't use the graphycal interface. Until the text terminals is impossible to access the unity interface. If I don't encounter a solution I will re-install the whole system. Anybody can help me?