I can’t say Colbolt. I was getting fed up with it so I replaced both the dominant directional light and the skylight with a fresh one ( I think Snipe recommended it) and worked through the settings watching the screen as I did so. The only setting I returned to the way I had it was using ‘don’t recompmpute static shadows’. I had that checkbox ticked and 'use global illumination unchecked. I had the dynamic shadow range set 20000 and in the skylight I had cast shadows unchecked (I don’t think it casts shadows anyhow) I worked down the list trying everything in the dominant light and when I reached cast static shadows the lines suddenly disappeared when I unchecked it. I checked it and they reappeared. I disabled the skylight so I could be sure it wasn’t being influenced by something else, but it done the same. It sort of made sense to me because I had don’t use precomputed shadows and the dominant light was casting realtime shadows then trying to use static shadows as well might be confusing it… Sorry it hasn’t worked for you… It’s bloody annoying. You’ll be pleased to know it was quickly followed by a different problem… The honymoon period is over…