It all started when I installed nvidia's own (download from website) driver. Uninstalling it and reverting back to nvidia-current didn't solve the problem, so I have been playing with this for a ...
I'm using Ubuntu 12.04 on my notebook (ASUS K53SV, i7-2670QM, Intel HD 3000, GeForce 540M). In order to save energy i've installed "bumblebee", a solution for Nvidia Optimus Technology on Linux. So ...