I'm running 11.04 on a 2011 13" mackbook pro (intel hd 3000 gpu).

Previously everything had been fine, but today when I plug in an external monitor (17" Acer being plugged in via a mini display port to VGA adapter) the laptop immediately recognizes the monitor, but the screen turns black. It seems that everything is still responsive. I can see the cursor and I can see it change as it moves over things like text boxes or the edges of open windows. But even after unplugging the monitor, I can't get anything but a black screen until I restart gdm.

Yesterday I was using the laptop with a 22" Asus monitor using a mini display port to DVI adapter and everything was fine. This same monitor was also working fine last week when I was running OS X, and on an older HP laptop without an adapter (straight to VGA).

How can I fix this?

  • Found any solution? Happening to me too in an Asus u35jc-a1, external monitor Samsung T220. At first I thought it was related to Unity, but it's happening in Gnome 2 as well. – Seb May 1 '11 at 21:45

Just found the official bug page, with possible workarounds such as installing other kernel versions: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/745112

For the time being, it seems we have to wait or play with other kernels...

EDIT: I've just installed and tried kernel linux-headers-2.6.39-020639rc4 and works like a charm - at least in this regard. I hope it's as stable as the previous one as well!


Installing a new 2.6.39 kernel solved a problem in my case. Here are step by step instructions for less experienced users: http://blog.lome.pl/blog/ubuntu-11-4-black-screen-problem-solved/

  • as mentioned in the comments on Seb's answer, no dice. The laptop monitor works fine with the newer kernels, but the external one is still a black screen. – gregghz May 3 '11 at 15:44
  • Did you try the one from here: launchpad.net/~kernel-ppa/+archive/ppa/+packages ? It's 2.6.39-rc5 not 2.6.39-rc4 so maybe it will work better... and it actually did work for me. – blazej May 4 '11 at 1:22

I am running Ubuntu 11.04 with both a Nvidia and an integrated Intel AGP in my laptop.

I am using an external monitor connected through a mini DisplayPort wired to the Intel card. It has been working since I installed Ubuntu 11.04 a month a go, today the external monitor stopped responding:

  • The external monitor reports no sync
  • System > Preferences > Monitors reports the external monitor as attached and operational.
  • Print Screen includes the image of the external monitor
  • The laptop primary monitor works as expected.

After double checking the cables, connections and the external monitor I booted back in the previous Kernel (I suppose yesterday I got an kernel update) and the external monitor came back to life. I did the test forth an back a couple times and the behavior was consistent.

The offending Kernel is 2.6.38-11-generic.

Last known good Kernel is 2.6.38-10-generic.

So far I am sticking to the previous Kernel while using an external monitor.

Following are my graphics device info:

anibal@collar-de-bolas:~ $ lspci | grep -i VGA
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: nVidia Corporation Device 0df4 (rev a1)
anibal@collar-de-bolas:~ $ sudo lshw -C video
[sudo] password for anibal: 
       description: VGA compatible controller
       product: nVidia Corporation
       vendor: nVidia Corporation
       physical id: 0
       bus info: pci@0000:01:00.0
       version: a1
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vga_controller bus_master cap_list rom
       configuration: driver=nouveau latency=0
       resources: irq:16 memory:f0000000-f0ffffff memory:c0000000-cfffffff memory:d0000000-d1ffffff ioport:3000(size=128) memory:f1000000-f107ffff
       description: VGA compatible controller
       product: 2nd Generation Core Processor Family Integrated Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:54 memory:f1400000-f17fffff memory:e0000000-efffffff ioport:4000(size=64)

As a workaround to be able to continue work, look here


You need to go to a tty shell (with no ui) by using, for example, ctrl+alt+F2. In the tty shell, you need to login and find any compiz process, using the command

ps -ef | grep compix

Then, kill all the compiz processes:

kill -9 <processes ids separated using space>

Then run unity to initialize the UI:


Give it a moment to load and go back to the 'UI shell', using ctrl+alt+F8, to see the UI being initialized.


I had this problem with a DVI monitor plugged into a dock, using Ubuntu 11.10. I solved it by deleting the file ~/.config/monitors.xml

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