I had my system crash this morning. After restarting the computer, everything appears to be OK. However, when I click on my normal user, and then enter my password, the monitor flashes and then I end up back at the GDM choice of users.
I can log in just fine as Guest. In doing some searching, there were some notes about deleting the .Xauthority file from the home directory. I did that, and then also deleted the lock file within the /tmp folder. After shutting the machine completely down, I tried logging in again. But, that didn't help.
If I hit ctl-alt-f1, I CAN log in to the shell, so I know my user does exist. Trying to use startx from here just gets me the msg about lock files.
Using Ubuntu 12.04 64bit