Using: nvidia-installer ncurses user interface
ERROR: An NVIDIA kernel module 'nvidia' appears to already be loaded in your
kernel. This may be because it is in use (for example, by the X
server), but may also happen if your kernel was configured without
support for module unloading. Please be sure you have exited X before
attempting to upgrade your driver. If you have exited X, know that your
kernel supports module unloading, and still receive this message, then
an error may have occured that has corrupted the NVIDIA kernel module's
usage count; the simplest remedy is to reboot your computer.
ERROR: Installation has failed. Please see the file
'/var/log/nvidia-installer.log' for details. You may find suggestions
on fixing installation problems in the README available on the Linux
driver download page at www.nvidia.com.