@dwagner:

Thanks for your comment. I could not reproduce the error with the 3fps 1080p
video on naked X. I let it run for 25 minutes without any issues. 

Besides, unlike yourself, I never experienced any sort of full system crash. I
can always shut down and reboot cleanly. 

As I mentioned, what happens, at random, is that the screens go blank and the
log shows the call trace I posted in the first message. But the system never
fully crashed so far. I can usually ssh into the box. Sometimes, a restart of
the desktop manager solves the issue, but more often a reboot is necessary.