Hi guys, Well today I was on public transport and my mid 2015 Retina 15" was freezing constantly and unusable. I shut it off and googled on the iPhone as you do and most results pointed to the SSD loose or RAM issue. Well it works perfectly stable and doesn't freeze when moving to the bedroom from the living room, I assumed therefore it must be something else. I removed all programs that weren't related to the fresh install to no avail. What happened next was weird, I wanted to reproduce settings so I walked up and down the street with the Macbook and sure enough it froze a lot of times, so I thought well what are the key things and they are: 1. Movement 2. Brightness changing automatically (constant during public transport) 3. Ambient light compensation I switched off both of these and sure enough same testing conditions no freezes, switched them back on kept walking and freezing. I don't know if anyone is mad enough to test the same it just renders my macbook pro unusable on public transport with this. The only thing I can't test unfortunately is if this is just an El capitan bug or my actual hardware as I haven't re-installed and really trying to avoid it. Anyone had issues or is this an isolated case?