My parents have an E370VA that's a little over a year old, and it has this same issue with a Charter cable box connected via HDMI. The thing is, they used it for about a year without the cable box, and it never had this problem. It also never does this when they are watching something else connected to the TV, like a DVD or Blu-Ray player. It only happens with the cable box, and they say it happens only on the HD channels. So all I can figure is that it is a fault with the TV that is somehow triggered by something in the signal from a cable or satellite box. It's an annoyance that I wish could be fixed somehow, but I don't think it's going to suddenly kill the TV (at least I hope not).
I am not usually around when it happens, but I'm wondering if maybe it happens when there is a momentary dropout in the cable signal coming into the box. Maybe the video or audio signal is lost for a split-second, and for whatever reason, this causes the TV to reset.