Comment 25 for bug 36596

"Possible fix" should be "Possible Workaround" and I forgot to add that I rebooted afterwards. I've now been running in Dual Head mode with s 1024x768x16 screen and a 1280x1024x16 screen without any problems for over an hour now. I've tried MPlayer, Firefox, Firefox + Flash 7.0 r63, Firefox + MPlayer Plugin, a couple 3D Screen Savers, and so far no problems whatsoever.

FYI, I've included my xorg.conf below. This is a lightly modified version from the one that was generated during the install to run a dual head configuration. Primary screen is the laptop and secondary is the monitor.

# /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 "ZAxisMapping" "4 5"
 Option "Emulate3Buttons" "true"
EndSection

Section "InputDevice"
 Identifier "Synaptics Touchpad"
 Driver "synaptics"
 Option "SendCoreEvents" "true"
 Option "Device" "/dev/psaux"
 Option "Protocol" "auto-dev"
 Option "HorizScrollDelta" "0"
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "stylus"
  Option "Device" "/dev/wacom" # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option "Type" "stylus"
  Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "eraser"
  Option "Device" "/dev/wacom" # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option "Type" "eraser"
  Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "cursor"
  Option "Device" "/dev/wacom" # Change to
                                                      # /dev/input/event
                                                      # for USB
  Option "Type" "cursor"
  Option "ForceDevice" "ISDV4" # Tablet PC ONLY
EndSection

Section "Device"
 Identifier "Radeon0"
 Driver "radeon"
 BusID "PCI:1:0:0"
 Screen 0
 Option "MonitorLayout" "LVDS,CRT"
EndSection

Section "Monitor"
 Identifier "Monitor0"
 Option "DPMS"
EndSection

Section "Screen"
 Identifier "Screen0"
 Device "Radeon0"
 Monitor "Monitor0"
 DefaultDepth 16
 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 "Device"
 Identifier "Radeon1"
 Driver "radeon"
 BusID "PCI:1:0:0"
 Screen 1
 Option "MonitorLayout" "LVDS,CRT"
EndSection

Section "Monitor"
 Identifier "Monitor1"
 Option "DPMS"
EndSection

Section "Screen"
 Identifier "Screen1"
 Device "Radeon1"
 Monitor "Monitor1"
 DefaultDepth 16
 SubSection "Display"
  Depth 1
  Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 4
  Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 8
  Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 15
  Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 16
  Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
 EndSubSection
 SubSection "Display"
  Depth 24
  Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
 EndSubSection
EndSection

Section "ServerLayout"
 Identifier "Default Layout"
 Screen "Screen0" 0 0
 Screen "Screen1" RightOf "Screen0"
 InputDevice "Generic Keyboard"
 InputDevice "Configured Mouse"
 InputDevice "stylus" "SendCoreEvents"
 InputDevice "cursor" "SendCoreEvents"
 InputDevice "eraser" "SendCoreEvents"
 InputDevice "Synaptics Touchpad"
EndSection

Section "DRI"
 Mode 0666
EndSection

Section "ServerFlags"
 Option "Xinerama" "true"
EndSection