Michael von Glasow, thank you for reporting this and helping make Ubuntu better.
Could you please run the following command once from a terminal by ensuring you have the package xdiagnose installed, and that you click the Yes button for attaching additional debugging information: apport-collect 1715749 When reporting xorg related bugs in the future, please do so via the above method. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs. ** Changed in: xorg (Ubuntu) Importance: Undecided => Low ** Changed in: xorg (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1715749 Title: Intermittent black screen on HP EliteBook 840 G1 Status in xorg package in Ubuntu: Incomplete Bug description: Occasionally, the internal laptop display goes black for a few seconds, then comes back to life. The external display stays on. It looks as if power management were kicking in by error but affecting only the internal display. When I’m working with the external display, I need to move the mouse into the area managed by the internal display to wake it up again; else it seems to remain black (though I haven’t tested that behavior thoroughly). Most tests with the external display were made with the port replicator and an external display plugged into one of the DP ports via a DP–DVI adapter. I cannot tell for sure what the behavior is with the external display plugged directly into the laptop. The hard disk was originally installed with Ubuntu MATE 14.10 in a HP EliteBook 6930p, upgraded to 15.04, 15.10 and eventually 16.04 and finally moved to the EliteBook 840 G1. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: xorg 1:7.7+13ubuntu3 ProcVersionSignature: Ubuntu 4.4.0-93.116-generic 4.4.79 Uname: Linux 4.4.0-93-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.10 Architecture: amd64 CurrentDesktop: MATE Date: Fri Sep 8 00:53:24 2017 EcryptfsInUse: Yes InstallationDate: Installed on 2014-12-09 (1002 days ago) InstallationMedia: Ubuntu MATE 14.10 "Utopic Unicorn" - amd64 (20141023) SourcePackage: xorg UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1715749/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : firstname.lastname@example.org Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp