Comment 7 for bug 145299

My procedures:

sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.orig
restart X (Press Ctrl-Alt-Backspace)

The X started properly and the <crtl>+<alt>+<fn> worked fine.

But when I did:
sudo dpkg-reconfigure xserver-xorg

and configured my video driver to nvida the <crtl>+<alt>+<fn> stopped to work.