What the heck are these?
This map was fine the last time I opened it, but now there are these green lines. I've run a basic python script to update layer symbology in between opening the map before and opening it now, but these lines haven't appeared in any of the other maps I ran the same script on.
The green mystery lines only appear in the layout view and they seem to go on forever. They don't seem to be associated with any of the layers in my map (I tried turning them off one at a time in the TOC). I can't select them or identify them. Closing and reopening the mxd doesn't help.
I had this problem too, the lines originate from an area on the ruler, when you zoom in and out the angle changes so that they are pointing to the same area on the side ruler.
I think these might be guides in your layout. The page layout help talks about them a bit. Try right clicking on the ruler on the left side of your layout and selecting Clear All Guides. Not positive, but would be worth a try.