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 -- xorg-server 1:1.0.2-0ubuntu10.3 breaks X: "no screens found" https://launchpad.net/bugs/57153 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs