ho provato a rifare la configurazione video tuttavia quando lancio startx dà errore:
xauth: error in lockin authoity file /home/gianni/.Xauthority
xauth: error in lockin authoity file /home/gianni/.Xauthority
xauth: error in lockin authoity file /home/gianni/.Xauthority
xauth: error in lockin authoity file /home/gianni/.Xauthority

Authentication failed - cannot start X server.
Perhaps you do not have console owership.

Sembra quasi che non abbia le permission...

Grazie