Comment 103 for bug 1431753

Indeed, I think I installed Bumblebee, because I thought that it would handle automatic switching between intel and nvidia as needed, but no way! it turns out it just allows you (or is supposed to allow, because I never managed to do even that) to manually run stuff on NVidia. So, in practice I have (or used to have until this update) bumblebee, nvidia drivers, and the intel GPU actually used all the time with the nvidia card just sleeping and useless. And I don't care, as long as my system doesn't start freezing every time I unplug the external screen.
All was fine (except for the errors showing up at kernel updates), and now everything is broken again (i.e. nvidia drivers being used, and causing random freezes because they don't support Optimus - or at least that's the diagnosis I was given when I first had the problem a couple of years ago)