Looks like some kind of encoding glitch--it's not dead pixels. Have you looked at the footage on multiple machines? Restarted? This would rule out a video card glitch on your edit machine.
In any event, it doesn't matter what it is--if you can rule out the possibility that your edit machine is introducing it, then you need to call a rental house for your upcoming shoots, and get this camera sent off to the shop!
This looks like digital noise. As Blaise stated above, rule out that it's your system doing it (sometimes can happen with the GPU).
I'd run some tests with your camera and see if you can reproduce the problem. I've had this happen before to footage and usually it's just a hiccup that happens. But you should run some tests with your camera to verify that it is or is not repeatable. If it is repeatable then you should send it in to Canon for some repair work.