I am trying to use Nvidia Optimus on my laptop by using Bumblebee, I have an Intel Core i5 with an Nvidia Geforce GT 630M. I have followed the instructions on the wiki page at https://wiki.ubuntu.com/Bumblebee, but when trying to run optirun with Firefox (or any other program, like glxspheres), I get the following error: [ 1921.452820] [ERROR]Cannot access secondary GPU - error: Could not load GPU driver [ 1921.452905] [ERROR]Aborting because fallback start is disabled. I have tried googling the issue but I couldn't find any solution that didn't cause more problems. Thank you for your time. Here is my bumblebee.conf: http://paste.ubuntu.com/1333324/