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.