I experience this on an ASUS 1001p netbook with 1024*600 internal and 1680*1050 external resolution as well. Will try the suggested fix to xorg.conf in a minute. What I've done so far is to disable one of the two displays with the monitor applet as a workaround.
** Summary changed: - [i945gm] Black video playback with dual screen enabled + [i915] [i945gm] Black video playback with dual screen enabled ** Changed in: xserver-xorg-video-intel (Ubuntu) Importance: Undecided => Medium -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in ubuntu. https://bugs.launchpad.net/bugs/460616 Title: [i915] [i945gm] Black video playback with dual screen enabled _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp

