All logins fail after running command

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http://askubuntu.com – I had a previous problem which I posted on this site, and was advised to try running the startx command when the login screen fails to load. I tried both startx and sudo startx But neither of them gave me anything but errors. However, after running them, I now get very strange behavior when trying to log into a session (which used to work fine as long as the greeter loaded). Now when I log on, I just get a blank black screen for a few seconds and then the Unity Greeter appears again. However, I discovered a very unusual way to log in, which will hopefully shed some light on the problem (HowTos)