This happens to me too (still) : both VGA and DVI-D (cannot test HDMI). This happens at both log-in and log-out.
DistroRelease: Ubuntu 16.04 Architecture: amd64 Date: Sat Mar 10 2018 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1281846 Title: Temporary black screen after login Status in lightdm package in Ubuntu: Confirmed Bug description: I turn on my laptop, wait lightdm appears, and do login to my user. Sometimes i got a black screen, only cursor appears in the screen. I can open a terminal with Ctrl+Alt+t, and run firefox using terminal, for example. And it is possible to change tty. Then, after 30 seconds, or more, like 1 minute, my desktop appears (background, unity launcher, top panel...). I'm having this problem in my asus laptop, that have nvidia optimus (and can confirm with other, a sony laptop with only intel graphics card). ProblemType: Bug DistroRelease: Ubuntu 13.10 Package: lightdm 1.8.4-0ubuntu1 ProcVersionSignature: Ubuntu 3.11.0-17.31-generic 3.11.10.3 Uname: Linux 3.11.0-17-generic x86_64 ApportVersion: 2.12.5-0ubuntu2.2 Architecture: amd64 Date: Wed Feb 19 00:52:59 2014 InstallationDate: Installed on 2013-12-13 (67 days ago) InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1) MarkForUpload: True SourcePackage: lightdm UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1281846/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp