aoane@aoa-nux:~$ sudo dpkg-reconfigure xserver-xorg
[sudo] password for aoane:
xserver-xorg postinst warning: overwriting possibly-customised configuration
file; backup in /etc/X11/xorg.conf.20080320034254
dexconf: error: cannot generate configuration file;
xserver-xorg/config/monitor/horiz-sync not set. Aborting. Reconfigure the X
server with "dpkg-reconfigure xserver-xorg" to correct this problem.
xserver-xorg postinst warning: error while preparing new Xorg X server
configuration file in /etc/X11/xorg.conf.dpkg-new; not attempting to
update existing configuration