Comment 5 for bug 766408

They removed that page from the appearance dialog :-/ however from the login screen you can select "Classic Desktop (No Effects)".

Those hangcheck timer elapsed errors are generic error messages indicating the gpu has hung in some fashion. Sometimes it is able to recover, in which case you won't see any noticeable effect.

What I'm wondering is if you have a video driver contesting the gpu with i915 (a common issue it seems).

I think this bug report probably should go upstream. But one thing to test, try disabling the i915 driver when you start things up (pass the kernel the option i915.disable=1).