I have a couple of problems with my inspire 1. I have done a compass calibration and an IMU calibration, as well as an RC calibration. I noticed that when flying forward with the inspire it doesn't make a straight line. It seems to drift one way or another. Is this normal? Why would it do this? Also, when I fly forward and release stick and the aircraft brakes it will sway to the left when it stops. When I reverse it does the same things to the right. Also, sometimes in hover the aircraft twitches. Weird stuff. Secondly. I was flying the other day and got a message that said "ultrasonic system failure. Land as soon as possible". After getting this the aircraft was hard to control but I was able to safely land it. I switched batteries and was fine. Today, I used the same battery and the aircraft started climbing by itself, and then when in hover it lowered itself several feet and had hard landing before lifting off again. I changed batteries and this was resolved. Sorry for long post. Please help if you can!!!