The recent ubuntu xorg update wiped out the NVidia libglx with a default one that crashes. It's likely only an issue with the NVidia vendor driver. A quick and easy resolution (see assumptions after these commands!) is:
sudo mv /usr/lib/xorg/modules/extensions/libglx.so /usr/lib/xorg/modules/extensions/libglx.so.orig
sudo ln -s /usr/lib/xorg/modules/extensions/libglx.so.331.20 /usr/lib/xorg/modules/extensions/libglx.so
This assumes you were running driver version 331.20. You can go to /usr/lib/xorg/modules/extensions/ and take a look to see what is there. You are basically replacing the default (which should be small) with the one provided by NVidia (which should be substantially larger).
Disclaimer: I handtyped the above commands based upon my setup (Kubuntu Saucy), they may contain typos, enter at your own risk, I am not responsible for puppies spilling out of your CD drive or any other malfeasance wrought upon your system.
Original klunky work-around:
The same thing is occurring to me. I managed to at least be able to log in by disabling all acceleration in KDE. Chrome still kills the desktop (as it uses acceleration as well). Something about this update killed the nvidia acceleration and anything that uses it instantly kills X.
Certainly not a complete answer, but possibly a useful and terrible work-around that may help you find a solution. (I'm using Opera right now, posting this as I seek a resolution myself).