"sudo service lightdm stop" will go into a blank screen
Solution 1:
Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:
If you are using GNOME:
sudo /etc/init.d/lightdm stop
to start again:
sudo /etc/init.d/lightdm start
If you are using GNOME:
sudo /etc/init.d/gdm stop
to start again:
sudo /etc/init.d/gdm start
If you are using kde:
sudo /etc/init.d/kdm stop
to start again:
sudo /etc/init.d/kdm start
Once you stop X, you need to get to virtual terminal. In Ubuntu its Ctrl+Alt+F1 - F7, to login, and gain access to the system.
Solution 2:
Here is another not so elegant solution that worked for me, I had same problem (still don't know why..): Just start up an ssh server before you kill the X server and do the driver install remotely from another machine.
Solution 3:
Try pushing Ctrl+Alt+F1 (or whatever the Mac has) and login to install your drivers