Comment 4 for bug 526955

I get a similar error message:

"
Unable to load X Server Display Configuration page:

Failed to query NoScanout for screen 0.
"

My solution was to edit /etc/X11/xorg.conf manually and add the line
Option "TwinView" "True"
to the device-section as mentioned in /usr/share/doc/nvidia-173/README.txt.gz