Welcome to the forum!
That's a really strange issue.
Crashing autoroutes, yes, that's intended and usually there's a reason for it.
But trade options added in from nowhere? Infecting further routes like a virus hidden in the trade menu?
To be honest I've never heard of something comparable to that in this game.
You don't use the copy-function for new routes, do you?
Maybe you use the trade routes in a special way nobody did so far? Can you give us a common example of how you setup your routes?
Anything you noticed to happen just before the game starts and keeps bothering by making autoroutes unplayable on its own?