Were you trying to export a map that you were making or just downloading a map and putting it in exports?
But either way, I think your best option it to try to go in your Feral Heart folder and getting rid of the exported things you made. Cause if the cause of it was when you exported something, chances are that's what you need to get rid of. If you can't find your Feral Heart folder then look in your (:C) local drive.
If all else fails then I think you just need to install the game all over again. So that way you know your screen will not bug on you
If nothing else and you have no idea what your doing you can always re-download FeralHeart. (Deleteing the old FeralHeart file) But I really recommend you trying to do what Feareh and WolfKate said first.