Update: I have found a workaround by .config/compiz-1 and .config/dconf (I have a backup of the .config/dconf if this might help to debug this issue, but not the compiz one, sorry). This makes the screen behave normally again...
** Attachment added: ".xsession-errors shows a whole multitude of problems starting with at-spi2-registryd respawning too fast, then indicator-sound aborting, then unity-settings-daemon aborting ..." https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1375194/+attachment/4221901/+files/.xsession-errors.old -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1375194 Title: lightdm session constantly switches screen appearance To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1375194/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs