https://askubuntu.com/questions/960517/ubuntu-17-04-loop-login-problem-for-default-desktop-environment/961536#961536 I have found out one reason for loop login, the reason was; I had installed Chrome Remote Desktop to my laptop. I uninstalled the chrome remote desktop, after that problem solved. Now I can login both desktop type Ubuntu Default and Unity8 without any problem. From terminal ctrl-alt-F3 write the command: "sudo apt-get autoremove chrome-remote-desktop" then reboot system
