On my Lenovo Thinkpad W520 I can switch between Nvidia Optimus or Integrated card. Since a couple of days, My Ubuntu doesn't start any more with the Nvidia card. The boot process stop itself at this point
And at this moment the fan runs at full speed (because the video card heats a lot, More than in a normal usage) and the disk is not in use.
I don't understand the correlation, But if I start on windows, I plug my monitor in the Display Port and I choose "Disconnect Projector", When I reboot, Ubuntu works (just one time)
How can I fix this problem?