I haven't seen anything like this ever (and the last piece of footage I shot was called MVI_5903-001).
Either your camera or the memory card are probably defective.

P.S.: I've never used Magic Lantern

hmm... looks like a trip to bangkok to see canon is in order...

Sorry for the delayed response. I haven't seen any artifacts remotely like that either.

I haven't tried to duplicate the problems I was seeing on a landscape shot with the 17-40 F4/L, but I have managed to improve the quality of the deep focus landscape shots with this lens. Now I am using the neutral picture style with sharpening and contrast all the way down and saturation down a notch. I am using Cineforms Neo HD and and First Light to convert and color grade the clips with final processing and sharpening in Vegas. I have eliminated most of the CMOS wobble with better camera handling techniques. The resulting wide angle shots look quite good.

Ironically, landscape shots with the 70-200 F4/L, 135 F2/L, and 300 F4/L IS look relatively soft and full of artifacts no matter what I do. Focus is spot on and checked with magnification in live view. Apertures are set to nearly ideal for sharpness in each case. I use low ISOs, have checked exposure, and set the shutter to 60 per second. It doesn't matter whether the camera is still or I slowly pan (on a tripod), the details are pretty soft (nothing in the frame but distant landscape features). In the same situations the still images are incredibly detailed and the Canon XH-A1 clips look great. Using the same lenses on the 5D II for closer subjects I get better detail, although not quite as much as with the XH-A1.

Consistent with many others' tests and observations, I've found the XH-A1 to have better effective resolution. Fortunately I never planned to use the 5 D II as a replacement for this camcorder. I gave up still photography 4 years ago when I bought the Sony HC-1. The 5D II gives me an opportunity to get back into it. In the next few weeks I hope to shoot some informal music videos in dark clubs with the 5D II, and learn how to take advantage of its strengths as a video camera.

Pat