Well, I have been working on a architectural visualization of part of my house, just for fun, and I decided that my main camera needed a skybox. So, I added a skybox component and used the default “Blue Sky” skybox. Suddenly, my doorways are glowing! And the edges are leaving render trails!
It’s nuts!
I’ve got some screenies for everyone, and a video for the dedicated. If you guys need them, I can host up the project files or a build.
Time to check if it has affected anything else, like maybe shadows! 
I would like to see the video.
BTW I noticed that Unity skybox is SLOWER in render than my sphere with self lighting material 
I got a similar issue replacing the cubemap by a 2D texture in the cubemap slot of the skybox material.
But it can’t help you i guess 
Hmm… looks like the .zip’d video I attached to begin with didn’t hold. I’ll put it up when I get home.
Probably best if other people can post their glithces of this sane kind too, more occurrences gets more attention 
Sadly for me, it’s not affecting anything else, which means no shadows or render to texture

I’ve seen this happen before when I was using CryEngine 2. Created a new scene and flew around the world and eventually this happened. Weirdest thing I ever saw.
Feel better now? 
Has anyone filed a bug report for this?