Forwarding this bug from Ubuntu reporter Oleksij Rempel:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/946311

[Problem]
Uses eDP1 rather than LVDS1 for the laptop panel.  When an external monitor is attached via VGA1 and RANDR used to tweak the config, the laptop panel loses its crtc and can't be enabled.

[Original Description]
This is regression after some recent (2-3 weeks) xorg? update.

I also tested newest kernel v3.3.0-rc6 with no changes.
I also tested kernel which worked before (3.2.0-12-generic), but it is not working now.

I tried beta1 : actually it works until I change the display configuration to disable one screen and try to re-enable both of them.  Then I can't get both screens to work again.
I tried beta 1 because IIRC back with beta 1 I didn't have any problem. but maybe it's just that I was lucky and didn't mess enough with the display configuration...

DistroRelease: Ubuntu 12.04
Package: xorg 1:7.6+10ubuntu1
Uname: Linux 3.3.0-rc6 x86_64
.tmp.unity.support.test.0:

ApportVersion: 1.93-0ubuntu2
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,decor,compiztoolbox,grid,gnomecompat,imgpng,mousepoll,regex,place,vpswitch,move,animation,snap,resize,session,expo,wall,ezoom,fade,workarounds,scale,unityshell]
CompositorRunning: compiz
Date: Sun Mar  4 13:56:04 2012
DistUpgraded: Fresh install
DistroCodename: precise
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu
GraphicsCard:
Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])
Subsystem: ASUSTeK Computer Inc. Device [1043:1427]
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120201.1)
MachineType: ASUSTeK Computer Inc. UX31E
ProcEnviron:
TERM=xterm
LANG=de_DE.UTF-8ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.3.0-rc6 root=UUID=ab2e9ae5-a032-44f5-b956-3223de09edff ro oops=panic panic=10 quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/20/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: UX31E.211
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: UX31E
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrUX31E.211:bd01/20/2012:svnASUSTeKComputerInc.:pnUX31E:pvr1.0:rvnASUSTeKComputerInc.:rnUX31E:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: UX31E
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.
version.compiz: compiz 1:0.9.7.0~bzr2995-0ubuntu5
version.ia32-libs: ia32-libs 20090808ubuntu33
version.libdrm2: libdrm2 2.4.30-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 8.0.1-0ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 8.0.1-0ubuntu2
version.xserver-xorg-core: xserver-xorg-core 2:1.11.4-0ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.99.901+git20120126-0ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20111219.aacbd629-0ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.17.0-1ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20111201+b5534a1-1build2