My Sky + Box turns itself over?

Every now and again our Sky + Box acts up, turns itself over, scans the channels, goes to the planner etc I thought it had something to do with our digisender so changed the channel and we have had no problems for about a month. Then on Friday it came up change the batteries (they hadn't been in long and were duracell +) the batteries were changed and since then it has started doing odd stings again. Any advice out there.