GDM isn't able to login

The login screen shows and i choose myself. Then the screen goes black, and the login screen shows again.

No answer, but this may be related to one of these two bugs:

Login Loop problem with 10.10

or Hitting send at login seems to restart X

I had a problem with GDM restarting (once) each time when trying to log in after upgrading to Maverick Alpha, upon installing GDM on top of an existing ubuntu Server install.

The solution for me was to remove GDM and GDM configuration files and reinstall.

ONLY RECOMMENDED if you can't get another solution.

I just had this exact problem with Linux Mint 10 Julia, which is based on Ubuntu. Login to tty1 console works, but not the graphical login (login loop as OP described).

The problem was in the /etc/profile file.

#... stuff   
if [ "$PS1" ]; then
  #... more stuff
fi

. /path/to/file/that/does/not/exist #raises an error and interrupts the login

umask 022

Once I removed the ". /path/to/file/that/does/not/exist" line, the login loop would stop and I could login to my desktop again.

So, make sure your .bashrc, .profile, /etc/profile files etc are clean and don't raise any errors that interrupt the flow.

Possible problem might have been that the /tmp directory has been removed or its permissions changed.

1. Press Ctrl-Alt-F1 and go to the terminal.
2. Create the directory by mkdir /tmp.
3. Change the permissions by chmod 777 /tmp
4. Ctrl-Alt-F7 and come back to the login screen and login.

A common source for this problem is a full harddisk. Try switching to a Terminal (CTRL+ALT+F1) and log in. Now run

sudo apt-get clean && sudo apt-get autoclean

which should give you some space. Now log out and go back to the graphical login-screen (CTRL+ALT+F7 or F8 or F9) and try again.

If you have a livecd, can you run a disk check (from the command line) on the disk? I've had systems do this before because of bad permissions, and a simple disk check fixed the problem.

Autologin worked fine for me, but not afterwards. I fixed it thanks to https://askubuntu.com/a/63697/42522

sudo dpkg-reconfigure -phigh xserver-xorg