Has anyone had problems with their SPOT II stop working? I rode Kokopelli trail this weekend and my spot just stopped working for no reason. New batteries were installed so I know that wasn't the problem. It didn't take any hard falls when it stopped working. I keep it facing up and go by the instructions. This is the second time I have had to replace it and need to figure out if anyone else has had the same issues. Wont send out a GPS signal any longer