I am no expert, by far, with the CK but I have run into the same issue as you have. Some of the things I've noticed have helped me with this problem. 1) If you have the Realistic Lighting or Realistic Torches mods, turn those off. I'm not 100% sure how to get it to work with them but I'm going to ask the author for help. 2) Make sure you don't have more than 4 lights overlapping each other (press L to see the light's radius). The CK Tutorial mentioned not being able to render more than 4 shadow omni lights at once 3) Some of my lights were 1/2 in a wall (they were torch lights) so I switched them to half-omni and that helped. 4) Some lights I replaced with "no shadow" casting lights and that fixed the issue. Another thought is that if you have two room in the same X/Y location but different Z locations (such as the first and second floor of a house) you might need to set room markers so that the engine doesn't render the entire location, and thus possibly more than the 4 shadow omni lights limit. Post back if these helped or didn't help you so we can get a community thread for others running into this problem. Thanks for responding! I´m going to try these methods and will post my answer later!!