Kubuntu 8.10 Video Flashing, Flickering, Blanking

Kubuntu Intrepid Ibex (8.10) on my laptop makes the screen flash on and off repeated every 10 seconds or so. The video output is actually turning on and off. It was driving me crazy. Here’s how to fix it.

My laptop has an Intel 945GM but this problem seems to affect other cards such as the GMA915 and some ATI as well. It has also manifested itself as flicker, rather than the periodic blanking that I’m experiencing.

According to bug 278471, this problem is associated with the monitor detection function in KDE4. So, to stop the flickering, flashing and blanking, simply turn off the detection service as follows.

  1. Click on the K menu
  2. Go to the Applications tab
  3. Click on the System menu followed by System Settings
  4. In the System Settings window, click on the Advanced tab
  5. Click on the Service Manager
  6. In the Startup Services list, select the service named, “Detecting RANDR (monitor) changes” so that it’s highlighted
  7. Click the Stop button to stop the service, then click the checkbox to clear it (so it doesn’t start up anymore)
  8. Click the Apply button

Voila! No more flashing. What a relief. After this bug is fixed, you can turn the service back on so that Kubuntu can detect monitors again.

30 thoughts on “Kubuntu 8.10 Video Flashing, Flickering, Blanking”

  1. Yes, thanks a lot! That did it for me too. PC with onboard graphics ATI Radeon HD3200 and Eizo TFT FlexScan L365 monitor.

  2. That’s great news, Edward. Thanks for the additional details on your system configuration. It helps others who may have the same or similar video card find the solution.

  3. Well, thank you too ^^

    Wouldn’t have found the bug nor the solution if it weren’t for your blog post 🙂


  4. woot. Your my hero. 🙂

    For future googling people:

    Radeon 3850 (RV670) using radeonhd driver on kubuntu 8.10. Fixes flashing black line that moves up the screen every few seconds.

  5. Thanks alot man… this really makes my movies watchable again. i was wondering.. how’d you come across this fix? i know i would have never found the solution..thats for sure.

  6. This hasn’t even vaguely solved any of the problem for me sadly.

    I’m running with a Mobility Radeon x2300 on a Sony Vaio VGN-CR42S/W if that’s any help.

    The distro is Kubuntu 8.10 with KDE 4.1

    Any help is appreciated!

  7. On an old Acer A80 desktop running kde 4 (from remix up to 4.1.2) the fix was to disable krunner.

    The problem applies ONLY to kde 4 krunner. Kde 3.5.9 does not have the same problem on this comp.

  8. Thanks dude!

    Fixed the problem on my Acer Aspire 1640 / 1644 as well.
    Don’t know what video card it uses, but I had something that appeared to flicker down the bottom of my screen as well.
    Fair play!


  9. didn’t work for me; flashing seems to decrease in frequency (didn’t time it), stopping krunner doesn’t do the trick either

    It didn’t happen in the beginning, then it started appearing somewhere during a session (kde or fluxbox). restarting the x server seems to stop the flashing for a while, until it starts all over again