Here is a variant of the above, and a solution - for THIS case, possibly helping in the other cases too.
SIDENOTE 1: if you do not run nvidia-settings with gksudo ... THE FIRST TIME (and do not have "$HOME/.config/ibus/" at that time) you will end up seeing:
IBUS-WARNING **: The owner of /home/$USER/.config/ibus/bus is not root!
Then refer back to
http://ubuntuforums.org/showthread.php?t=2140352 - then delete the .../ibus/ directory (note NOT .config/) and continue here...
SIDENOTE 2: you may also see:
** (nvidia-settings:8563): WARNING **: PRIME: Failed to execute child process "/usr/bin/prime-supported" (No such file or directory)
** Message: PRIME: is it supported? no
The remedy is to do
sudo apt-get install nvidia-prime
... which was BROKEN for some time, but seems to be back "online" again.
SIDENOTE 3: Unless you have e.g. DUMMY like this:
$ tail -n 3 /etc/group
nvidia-persistenced:x:128:
DUMMY:x:65535:
(hrm, that
is three lines, even if doesn't look like it) ... then you will NOT have color-profiles loaded for your EXTRA displays - in a multi-display setup - on startup. The problem is the LAST LINE in /etc/group - that group will not "work".
The following has a direct relation to not being able to save changed settings:
$ gksudo nvidia-settings
ERROR: nvidia-settings could not find the registry key file. This file should have been installed along with this driver at either /usr/share/nvidia/nvidia-application-profiles-337.25-key-documentation or
/usr/share/nvidia/nvidia-application-profiles-key-documentation. The application profiles will continue to work, but values cannot be preopulated or validated, and will not be listed in the help text. Please see the README for possible
values and descriptions.
... is that familiar? Then do
sudo bash
...
mkdir -p /etc/nvidia
cd /etc/nvidia
ln -s /etc/alternatives/x86_64-linux-gnu_nvidia_app_profile_keys nvidia-application-profiles-340.24-key-documentation
ln -s /etc/alternatives/x86_64-linux-gnu_nvidia_app_profile nvidia-application-profiles-340.24-rc
Then check that you can see something similar to:
$ ls -l
total 0
lrwxrwxrwx 1 root 58 jul 12 14:23 nvidia-application-profiles-340.24-key-documentation -> /etc/alternatives/x86_64-linux-gnu_nvidia_app_profile_keys
lrwxrwxrwx 1 root 53 jul 12 14:23 nvidia-application-profiles-340.24-rc -> /etc/alternatives/x86_64-linux-gnu_nvidia_app_profile
Note that "-340.24..." and maybe other parts may differ for you (depending on version of the driver), what is shown is after installing the very latest from the xorg-edgers ppa at this writing.
The standard Ubuntu NVidia drivers generate some problems on slightly older and slightly newer NVidia hardware.
If you want more then the standard Ubuntu repository drivers, install the xorg.edgers PPA.
sudo apt-add-repository ppa:xorg-edgers/ppa
sudo apt-get update
As the xorg.edgers group ask not to give installation instructions directly without linking to their page, this is the best I can do (for now).
If you don't know what a PPA is or need some guidance after reading their page, leave a comment below.
Best Answer
The compiz fix suggested here solved the problem for me.