This problem can be occurred at two instances. 1. Fresh installation: 1. Download the driver from nVidia website 2. Copy the file to the disk. (It looks like "NVIDIA-Linux-x86_64-319.17.run", depends on your version) 3. Now just type the following command from terminal: sudo sh ./NVIDIA-Linux-x86_64-319.17.run 4. Follow the on-screen instructions and finally reboot. 2. Problem after upgrade: 1. Login into command prompt 2. Run the following command: sudo sh ./NVIDIA-Linux-x86_64-319.17.run 3. It will ask to delete previous installation. Accept all the prompts and also the one to edit xconf file. 4. Finally it will reboot and system boots normally. After successful boot, you can configure your driver in the System>Preferences section. Other work-arounds: 1. When prompted the low graphics mode, select the "Restart X" option. This will work in some cases. But every time you boot, perform the same. 2. Also try blacklisting "nou...