desktop is a different story. the issue happens when you have both intel and nvidia gpus.
see for example:
https://devtalk.nvidia.com/default/topic/790089/linux/nvidia...
http://askubuntu.com/questions/372686/after-installing-nvidi...
see for example:
https://devtalk.nvidia.com/default/topic/790089/linux/nvidia...
http://askubuntu.com/questions/372686/after-installing-nvidi...
I analyse the problem and present a hacky work-around in this post: http://vxlabs.com/2015/02/05/solving-the-ubuntu-14-04-nvidia...