I have got several crashes after changing mode. There are several different ways this happen, but I suspect they have some similarities.
I got one after shooting a pic in Av (non live-view), then changing to A-dep (remappe as movie mode). I then started to record a clip, but after a very short time, the buffer went full. It was somewhat like having fps-override and recording audio.
Still investigating if I ca find a reliable way to reproduce it.
Update: When starting in photo mode(e.g. Av, M, etc), and then starting recording after switching over to A-dep (remapped as movie mode), I get consequent crashes. Canon FW says Err70, and ML gives a error message looking like the uploaded file. (Probably familiar) Battery does not have to be removed.