grep EE /var/log/Xorg.0.log
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(II) Loading extension MIT-SCREEN-SAVER
(EE) Unable to open /usr/X11R6/lib/modules/extensions/nvidia/libglx.so
(EE) Failed to load module "/usr/X11R6/lib/modules/extensions/nvidia/libglx.so" (open failed, 2)