Have just had it in operation for a couple days now and this afternoon it did something strange 2 times. I had it set on full screen sonar, setting still in about 15 ft of water. All of a sudden I hear it beep and it is back to the GPS screen and I have to reselect the full sonar screen again. It did this 2 times this afternoon. I was not in front of it at the time so I didnt see it make the change but it beeps each time it did it. Anybody else have this problem??