The lighting in my custom dungeon acts a bit strange. All objects (Items, npcs, etc.) lightened by certain light objects I've placed near them all appear with ugly stripes all over the place.

http://postimg.org/image/hf9tx0b3j/

http://postimg.org/image/46n0c4uyn/

How do I get rid of that problem, while still lighting up the specific objects?