How can I get rid of this black screen?

I have this black square randomly appear on builds I make. It can be fine, I save and go to the worlds screen and sunddenly this black square appears, blocking a section of the build. When I then go into the lot I can build and play normally except when I turn to the area the black square is in the world screen, the screen freezes and sometimes my computer stops responding. It is not visable itself when you play in the lot, but has the aforementioned affects. It does not go away when I fix the game, or close the game, and is not being caused by Mods or CC as I do not have any. It also can be seen in the personal galley so you cannot save the lot and get rid of it, by bulldozing the lot and putting it down. I does not affcet saving rooms, but that is not always possible to save and it tedious to reconstruct builds using  individual saved rooms.