I was also affected by the problem, and since I noticed that the "Monitor" section in /etc/X11/xorg.conf contained just two lines[1] (as it is the case in the xorg.conf file posted above by Sergio Oliveira), I have performed dpkg-reconfigure xserver-xorg several times to no avail. Thanks to the solution posted at ubuntuforums.org I installed manually the corrected package and everything was happily fixed.
I was also affected by the problem, and since I noticed that the "Monitor" section in /etc/X11/xorg.conf contained just two lines[1] (as it is the case in the xorg.conf file posted above by Sergio Oliveira), I have performed dpkg-reconfigure xserver-xorg several times to no avail. Thanks to the solution posted at ubuntuforums.org I installed manually the corrected package and everything was happily fixed.
Credits go also to Rodrigo for the quick fix!
[1] these:
Section "Monitor"
Identifier "Generic Monitor"
Option "DPMS"
EndSection
instead of (currently working):
Section "Monitor"
Identifier "Generic Monitor"
Option "DPMS"
HorizSync 30-86
VertRefresh 50-160
EndSection