I have a Dolphin Nautilus that I have had for about a year now. Recently, it has gotten to where it will just stop and not move. The power light on the power brick is still illuminated also. I can turn it off, unplug it, plug it back in, and turn it back on and it does it's thing. The good news is that it isn't every time, only occasionally. But it does seem to be happening more frequently, which has me nervous.