Upgraded from 12.04 to 13.10. Seemed to go OK, but when rebooted the login screen was very low resolution with trailing mouse, so purged the Nvidia drivers, then reinstalled via PPA as in www.howopensource.com
Seemed to go OK (no screen errors, the login screen is now normal resolution) but when I login it loops back after a minute to the login screen again.
I can login using CTRL+ALT+F1
The Guest account has same problem.
.XAuthority and reinstalled XOrg as mentioned here: Ubuntu 13.04 Login Loop
Installed GDM as here: https://askubuntu.com/questions/130387/stuck-at-login-screen but it failed to load (could only login into TTY)
NVIDIA(0):Failed to initialize the GLX module; please check in your X log file that the GLX module has been loaded in your XServer, and that the module is the NVIDIA GLX module. If you continue having these problems, please try reinstalling the NVIDIA driver.
lspci -nnk | grep VGA -A1 shows:
01:00.0 VGA compatible controller :NVIDIA Corporation GT218 [Geforce 210] [10de:0a65] (rev a2) Subsystem Gigabyte Technology Co., Ltd Device [1458:34d5] 02:00.0 VGA compatible controller :NVIDIA Corporation GT218 [Geforce 210] [10de:0a65] (rev a2) Subsystem Gigabyte Technology Co., Ltd Device [1458:34d5]
Was running 12.04 on this machine for more than a year.