View: https://www.youtube.com/watch?v=K1g9ImC5cJQ Just what is going on and what would be the actual culprit of the the three things - monitor, mac mini (video card / TB port / cable) or Lightroom? The fault as you see occurs when selecting that particular image and disappears as soon as you click another one. It stopped doing that after a while. These sort of things are happening more and more often now. I am sure I'll just change the hardware after a while anyway.