I'm having quite regular crashes - no rattles or anything. Looks like software to me. Twice it has locked up and needed several holding-downs of the power button for >15s to make it do anything. In between it works fine. Lots of other less extreme crashes (i.e. where it reboots itself).
Not had it happen on straight page turns - tends to be when moving the cursor for dictionary look-up or to follow a reference.
Hope they release some fixes soon. I checked that all the indexing had finished, and these are all subsequent to that.