Captain Sarcastic Can you try something.
In synaptic, do a complete removal of prelink, it will take a couple of minutes.
Dont reboot, just see if Iron will then work.
That did it! Now I'm just mildly concerned about having both Iron and Chromium installed, but removing prelink made Iron fire right up again.
Thank you, uggy!
CaptainSarcastic, Glad you got it sorted.
Vortex, I think there are different issues here, I & others had problems with Chromium, Iron & KDE crashes etc, after nvidia updates. Prelink runs itself in background, then comp goes potty! 
In LXDE I found that changing Nvidia driver to 280 (rebooting) fixed the Chromium segfault problem. Changed back to 290 and Chomium continued to work until about the 2nd or 3rd reboot. Followed the suggestion to remove prelink and with the 290 driver have had no more Chromium problems.
FullMonty installed on the same computer has been running with the 290 Nvidia driver plus prelink for a long time without any problems with Chromium.