Hey, someone posted in my thread about this issue. It's caused by they "Enhanced Lighting and FX" mod. Disable for this part of the game then you can turn it back on. The mod creator knows of the issue and is working to correct it.
I'm having this same issue that I posted about earlier. Looking at your mods we have a few similar installed mods but none of the ones I have installed modify Skyrim's graphics beyond the characters. I've been unable to find a solution at this point but at least we aren't alone in this! lol
So I've come across a graphical glitch during Diplomatic Immunity quest that I can't seem to find any information on. Any one else encountered this and know how to get past it? Here is a screen of what I'm getting. I'm unable to go through the door because of this glitch. I've tried going back a couple saves but it's still there. http://i32.photobucket.com/albums/d39/manzikeen/ScreenShot2_zps79d2b456.png