I don't know what should be in /etc/profile, so I've just attached it. I'll reboot now and explicitly choose xfce4-session.
** Attachment added: "/etc/profile" http://librarian.launchpad.net/6918149/profile -- After boot, my first login automatically logs out https://launchpad.net/bugs/94440 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs