I'm getting periodic lockup with my 1DsMk11 and 70-200 2.8 IS. I turn off the camera, remove and re-attach the lens and everything is ok again. Its happening a little more frequently lately. Has anyone here experienced this? Is there a fix?
Let's see... is it ERR 01 or ERR 99? :-)
Either way, I think it's a known issue with some 70-200s that are more than a couple years old. I had the same problem (it really only happens in IS mode), and sent the lens to Canon and they fixed the issue. Or I should say, I haven't experienced the issue since I sent it back -- that was a couple months back and I've taken a few hundred shots with it since.