Sometimes, users can't login to their Ubuntu session and each time they insert their account credentials and press Enter, the login screen loads again, only the guest user session can be accessed.
If you can't logon to your account under Ubuntu 11.10, you may try this solution which will help you fix this bug that is most common after an upgrade. You should know that not all users will solve this problem with this tip, but I wish you good luck!
1. At login screen, press Ctrl+Alt+F1 to switch to console mode.
2. Use your username and password to login.
3. Enter now these commands:
ls -Shla | grep “Xauthority”
sudo mv .Xauthority Xauthority.old
sudo shutdown -r now
If you have more solutions or suggestions, use the comment form given below.