Maybe this should be in the Games forum, but that seems more dedicated to "serious" games. I'm concerned here with a couple of the Linux standards - TuxRacer and Chromium - which have stopped working. They ran OK when I first installed MDK10 recently, but when I went to demonstrate them to my son last night they wouldn't run. The panel says "Starting TuxRacer", but then it disappears after about 10-15 seconds and the game doesn't open. Same with Chromium.

The only change that I have made to the basic MDK installation is to install the nVidia drivers - could this have had some effect on these games?

Moved: This thread is more suitable in Linux - Games and has been moved accordingly to help your thread/question get the exposure it deserves.

Run the games by typing the name of the executable in a shell console, like konsole. Then, tell us what output you receive. My guess is that the XFree86Config-4 file needs manual tweaking.

Running the executable from the command line gives the error -

Could not open /dev/nvidiactl because the permissions are too restrictive. Please see the FAQ section of /usr/share/doc/NVIDIA_GLX-1.0/README for steps to correct.

I checked the FAQ which gives the following answer -

A: It is likely that a security module for the PAM system may be
changing the permissions on the NVIDIA device files. In most cases
this security system works, but it can get confused. To correct this
problem it is recommended that you disable this security feature.
Different Linux distributions have different files to control this;
please consult with your distributor for the correct method of
disabling this security feature. As an example, if your system has
the file
/etc/security/console.perms
then you should edit the file and remove the line that starts with
"<dri>" (we have also received reports that additional references to
<dri> in console.perms must be removed, but this has not been verified
by NVIDIA). If instead your system has the file
/etc/logindevperms
then you should edit the file and remove the line that lists
/dev/nvidiactl. The above steps will prevent the PAM security system
from modifying the permissions on the NVIDIA device files. Next,
you will need to reset the permissions on the device files back
to their original permissions and owner. You can do that with the
following commands:
chmod 0666 /dev/nvidia* chown root /dev/nvidia*

I'll try editing the necessary files as suggested (presumably as root) and see if that does the trick. Thanks for the suggestion of running from command line to see what error message is generated.

OK,...

You probably set the security on the machine to high. You probably only need the security settings to be set to the default, or at most, moderate level. Higher levels ofsecurity are mostly for Internet and mySQL servers, without desktop stuff running.

Depending on your experience with Linux, you can also try changing the ID # of the X-window system to a lower setting, in order to raise it's presumed security priority. But from the sounds of it, I wouldn't try messing with that. Just try going to your security settings in the configuration utilities and lowering them a bit. Even at that level, they should be adequate to protect your system against the average web-based attack.

My experience of Linux is minimal and that edit to /etc/security/console.perms completely screwed things up. I managed to boot the system into failsafe/single user and re-edit console.perms back to its original form. This has got things running OK again and - surprise, surprise - the GL games now work. Must have been the chmod and chown changes that did the trick.