I have a new precision cooker, i've used it 3 times prior to today without incident. when i started the unit today, i set the temperature at 127 and it ran for about 3 minutes, then the water stopped circulating and a steady alarm sounded. I thought i may have had it too close to the corner of the cooler i use it in, so i repositioned it, to no avail. i unplugged the unit and let it sit for 3 minutes, still the same result. what's happening? the water level is more than adequate.