Sometimes after you load Linux on your hard drive, you might have
 trouble rebooting.  You just can’t get past the login.  This means
  your Xserver needs rebuilding.  Yes, a bug. Sigh.  So here’s what you
  do:

Press down Alt & Ctl at same time
Hit F1,F2 or F3 (these keys allow different logins outside of normal
  desktop environment—see below note)

Have to be root  user so at prompt type:  
su
 pwd:  fab

next prompt:
apt-get install x11-common

It will start to load stuff and then it will ask:
Keep current version? 
You say: No

At next prompt type: (first letter is a lower case L)
 ln -fs /etc/init.d/x11-common /etc/rcS.d/S70x11-common

reboot machine after this loads

You should be set!



NOTE:
There are a total of 7 linux logins running on each computer.  F1, F2,
  F3, F4, F5, F6 and F7.  If you are in a session and someone else 
 needs to get on your computer and do their own quick thing and get
  out again, they can use one of these logins—from desktop
  press down Alt & Ctl 
And at same time
Hit F1,F2 or F3 …
This will take you to another login.  F7 is the login with the graphic
  interface that you are used to seeing and working in…
To get out of the extra login, type “exit” at the prompt.