Mine does the same thing, but only if you're not having a very good game. I am not really sure where the cut-off point is but I notice if I don't break a fifty or a hundred million I get the automatic avalanche. Maybe changing the difficulty setting will change this, but I am not sure as I haven't dinked around with the settings too much. Mine is pretty easy to get an extra ball as well, but I like it easy as it lets my kids get an extra ball here and there, and let's pretty much everybody experience the multiball on that game.