Well... try remove xserver-xorg and reinstall it: sudo aptitude purge xserver-xorg sudo apt-get install xserver-xorg-core=2:1.10.4-1ubuntu4.1
After reinstalling xserver-xorg the problem of missing.
Well... xorg-core= 2:1.10. 4-1ubuntu4. 1
try remove xserver-xorg and reinstall it:
sudo aptitude purge xserver-xorg
sudo apt-get install xserver-
After reinstalling xserver-xorg the problem of missing.