Comment 20 for bug 22976

default (unedited) xorg.conf, that does not work, is the one generated by the live CD:

# /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the /etc/X11/xorg.conf manual page.
# (Type "man /etc/X11/xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg

Section "Files"
        FontPath "/usr/share/X11/fonts/misc"
        FontPath "/usr/share/X11/fonts/cyrillic"
        FontPath "/usr/share/X11/fonts/100dpi/:unscaled"
        FontPath "/usr/share/X11/fonts/75dpi/:unscaled"
        FontPath "/usr/share/X11/fonts/Type1"
        FontPath "/usr/share/X11/fonts/100dpi"
        FontPath "/usr/share/X11/fonts/75dpi"
        # path to defoma fonts
        FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
        Load "i2c"
        Load "bitmap"
        Load "ddc"
        Load "dri"
        Load "extmod"
        Load "freetype"
        Load "glx"
        Load "int10"
        Load "type1"
        Load "vbe"
EndSection

Section "InputDevice"
        Identifier "Generic Keyboard"
        Driver "kbd"
        Option "CoreKeyboard"
        Option "XkbRules" "xorg"
        Option "XkbModel" "pc104"
        Option "XkbLayout" "us"
EndSection

Section "InputDevice"
        Identifier "Configured Mouse"
        Driver "mouse"
        Option "CorePointer"
        Option "Device" "/dev/input/mice"
        Option "Protocol" "ExplorerPS/2"
        Option "Emulate3Buttons" "true"
EndSection

Section "Device"
        Identifier "ATI Technologies, Inc. Rage 128 PR/PRO AGP 4x TMDS"
        Driver "ati"
        Option "UseFBDev" "true"
EndSection

Section "Monitor"
        Identifier "Generic Monitor"
        Option "DPMS"
        HorizSync 28-51
        VertRefresh 43-60
EndSection

Section "Screen"
        Identifier "Default Screen"
        Device "ATI Technologies, Inc. Rage 128 PR/PRO AGP 4x TMDS"
        Monitor "Generic Monitor"
        DefaultDepth 24
        SubSection "Display"
                Depth 1
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth 4
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth 8
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth 15
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth 16
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
        SubSection "Display"
                Depth 24
                Modes "1024x768" "800x600" "640x480"
        EndSubSection
EndSection

Section "ServerLayout"
        Identifier "Default Layout"
        Screen "Default Screen"
        InputDevice "Generic Keyboard"
        InputDevice "Configured Mouse"
EndSection

Section "DRI"
        Mode 0666
EndSection