After placing track and switches, in route layer, fine tuning signals I'm ready to have a go at a session.  I place the locos with rolling stock and proceed to run the route.  Everything is fine until I save the session.  Later, when I want to continue the session I find that the switches are in the middle of the track, the arrows are pointing in the direction of the track and the arrows are red.  Some track spline points have a kink in them.  I've gone back into the route session and fixed the offending switches and track and sometimes they're fixed until I save a session again.  It's not always the same switches or tracks.  It seems to be random.  What's going on here?
				
			
 
	