Recently, on mountain bike rides/races specifically, my 820 will just randomly change screens. I'll look down to check my progress on the course and the drop down menu from the top bar will be the only thing visible, or it will have changed to one of my settings screens, one of the data fields on the correct screen might be selected/blackened as if I'm trying to change the data field to something else entirely... I cannot stress enough how frustrating this flakiness is when in the middle of a race and trying to gauge distance, speed, progress, etc.
I've only seen it happen a few times on road rides, but almost always on a MTB ride I will look down to see a screen I did not select!
