Try CTRL+ALT+F1 @ your login screen of Ubuntu, and then log-in using the shell, it should generate a new .ICEauthority file for you.
When login using the shell works, use the following command:
Code:
ls -l .ICEauthority
To see wether a new file has been created, and wether the owner and group match your username!
If all is correct, first logout from the shell, then hit CTRL+ALT+F7 to go back to your login screen, and try logging in!
good luck.