I have a Dell XPS 15z laptop. As you can see here, there are some issues with NVidia drivers. The site recommends installation of Bumblebee (instructions given in the link). I am posting it again for ease: $ sudo add-apt-repository ppa:bumblebee/stable $ sudo apt-get update && sudo apt-get upgrade $ sudo apt-get install bumblebee bumblebee-nvidia $ sudo usermod -a -G bumblebee $USER

After restarting the computer however, the screen resolution was stuck at 640x480 and I got the following error message as soon as I logged in:

**Could not apply the stored configuration for monitors**
none of the selected modes were compatible with the possible modes:
Trying modes for CRTC 63
CRTC 63: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 0)
CRTC 63: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 1)
Trying modes for CRTC 64
CRTC 64: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 0)
CRTC 64: trying mode 640x480@60Hz with output at 1366x768@60Hz (pass 1)

Prior to the update, the display was absolutely normal and thus there is no doubt about the cause. Albeit, there was no support for graphic drivers. In case it helps, some features of graphics drivers seem to be functional after bumblebee, ie, all features are in order except for the resolution.

And if the resolution can't be fixed, please suggest a way to retract the changes so that atleast the prior state may be reachieved.

Any help in the matter would be highly appreciated.