blank screen after update

Ubuntu 14.04.3

$ sudo apt-get install nvidia-prime
$ prime-select query
$ sudo prime-select intel

(and I deleted /etc/X11/xorg.conf, for better or for worse.)

Problem solved!

Found a very detailed account and solution posted by Dr Charl Botha of vxlabs:

• https://vxlabs.com/2015/02/05/solving-the-ubuntu-14-04-nvidia-346-nvidia-prime-black-screen-issue/

Sidenote: /usr/bin/gpu-manager is from the ubuntu-drivers-common package.