I'm having the same problem on a fresh install of 9.04. I installed the restricted nvidia driver 180, rebooted, configured the dual monitors via nvidia-settings and get the same error as above.
Running nvidia-settings with gksu didn't help but from the terminal I see the following: VALIDATION ERROR: Data incomplete in file /etc/X11/xorg.conf. Undefined Device "(null)" referenced by Screen "Default Screen". The original xorg.conf is attached. I added the following line to the "Screen" section and now nvidia-settings is working correctly: Device "Default Device" It appears that nvidia-settings is behind X in its guessing ability and simply gives up when no video device is specified under Screen. X, on the other hand, seems to march through the file and just grab the first available device. Also of note, you have to run nvidia-settings as root (gksu nvidia- settings) or you won't have permissions to save the X files anyway. Perhaps those devs could have it prompt the user for a password or ubuntu devs could have it do the same on launching? ** Attachment added: "xorg.conf" http://launchpadlibrarian.net/26954057/xorg.conf -- Fails to parse xorg.conf https://bugs.launchpad.net/bugs/366360 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs