Cliff, just came across this on my mega factory I am working on. When trying to lay down a long line or ground conveyors, or overhead conveyors, and I drag it to the edge of the map / build area, it crashes the game. But only on this Custom made map I made a while back. Other Maps I made from the same time, do not crash. So thats good News, I can only repeat it on this one Map.
Image of the error
Just Drag a conveyor to the edge of the primary build area and it should do it. Not sure if this may help ID something that can be causing another issue people may be having. For me, I know I just need to Make a New Mega Factory map