I upgraded my installation from 13.10 to 14.04. The problem is that whenever I install the Nvidia drivers from the GUI, upon reboot or trying to login again it only shows the wallpaper of my desktop and nothing else. The mouse does move around, but nothing works. I am unable to open a terminal or do anything else. If I go into the tty console and purge the drivers, then things seem to work again. I have an Optimus setup, with an onboard Intel and discrete Nvidia GTX770M card. It's a 64-bit architecture. I really need to work with CUDA, and was hopeful after hearing that nvidia-prime was released, but this is a real downer. Any help on this?