Comment # 3 on bug 991282 from Kyle Agronick

I am having the same issue. I have an Optimus laptop and I am using bumblebee
with intel-virtual-output. I have seen this issue as well.

When it restarts really fast it is X trying to start over and over again. You
can barely type. Like 1/4 of keystrokes go through. Deleting what caused it
lets X start normally. nvidia-xconfig writes a bad X config on optimus laptops
which can cause this. Every laptop I've had running nvidia-xconfig causes this.
(All have Optimus) Even on Leap.

I have also seen it blink much slower. I think that is an unrelated issue. I
saw it happening after unplugging a monitor.