You can log in a "real" terminal (I am not talking about a "virtual" terminal
that you would launch from a graphical desktop) by pressing Ctrl+Alt+F1 after
the initialization of the system (i.e., once you are presented the login
screen), then entering your user name, and, finally, your password. From
there, you can type 'sudo service lxdm stop' to stop the display manager and,
finally, 'startxfce4' to attempt the launch of Xfce.
By reporting here what happens (is Xfce properly launch?; if not, what is the
error message in the terminal?; etc.), we will have a better understanding of
the issue. In particular, we are trying to know whether Xfce itself raises a
problem or whether it is only about configuring the display manager (which is
bypassed when you run 'startxfce4' from the real terminal).
Understand the problem is the first step to fix it. If we succeed, you will
then be able to "comfortably" login from a graphical screen.
