I have a Dell Inspison 9100(laptop) with a Dell 2005FPW LCD. I was able to
configure dual-display to work perfectly but unfortunately today i might have
burned my laptop's screen.
When i rebooted, the primary display became my LCD instead of the laptop's
display which didn't turn on and once gdm came up, the laptop's lcd displayed
some weird patterns .
At this point I directly  rebooted and my laptop's display been black since
then. Even if i unplug the external monitor it stays black. i tried running
windows on it with the same result. I am not sure if the display is just off or
burned.

I am not sure if this bug is similar to Bug#1620


My xserver version:
xserver-xorg   6.8.1

Relevant section of my xorg.conf
Section "Device"
        Identifier      "ATI Technologies, Inc. Radeon Mobility 9600/9700
M10/M11 (RV350 NP)"
        Driver          "ati"
        BusID           "PCI:1:0:0"
        Option     "DDCMode" "on"
        Option     "MergedFB"     "true"
        Option     "MonitorLayout"      "LVDS,TMDS"
        Option     "CRT2Position"  "RightOf"
        Option     "CRT2HSync"      "30.0-83.0"
        Option     "CRT2VRefresh"    "56.0-75.0"
        Option     "MetaModes" "1920x1200-1680x1050"
EndSection
Section "Monitor"
        Identifier      "Generic Monitor"
        Option          "DPMS"
EndSection



Relevant output of "lspci -v" 

0000:01:00.0 VGA compatible controller: ATI Technologies Inc RV350 [Mobility
Radeon 9600 M10] (prog-if 00 [VGA])
        Subsystem: Dell: Unknown device 017c
        Flags: bus master, VGA palette snoop, 66MHz, medium devsel, latency 255,
IRQ 16
        Memory at f0000000 (32-bit, prefetchable) [size=128M]
        I/O ports at c000 [size=256]
        Memory at fcff0000 (32-bit, non-prefetchable) [size=64K]
        Expansion ROM at 80000000 [disabled] [size=128K]
        Capabilities: [58] AGP version 3.0
        Capabilities: [50] Power Management version 2