I would start by resetting both tools insert edge and move tool if that does not work delete your preference file ( maya will make another one when you restart it ) let us know how you get on, the black lines could be your graphics card..............dave Thanks dave. Reseting those tools didn't work, but deleting the prefs folder did. I still don't know how did I mess up my settings before. I guess I have to be more careful with my keyboard.