I must add that the upgrade to Xserver 1.20 was at the same time as the Nvidia upgrade & the problem occurred right afterward (the xserver upgrade was blocked until there was a xserver-xorg-video-nvidia package available). Looking at the commit in question, I see that the Xserver is no longer looking for /linux--the location that Nvidia installs its version of libgxl.so. After creating a link from /linux to /extensions to make the nvidia driver work correctly "tends" to make me think that the root cause has been found.
I am very open to exploring other options & will help in anything asked. -- Cheers!!! Dean Loros Performance by Design Ltd. autocrosser at http://forums.linuxmint.com