Tried to enter Falkreath Barracks last night, and immediatley starting falling through the floor. Re-started and the same thing happened. I've played through 16 hours with relatively few problems... this came out of nowhere.

I'm not sure if this could be related to a mod or not, but here's my load order:

http://i48.tinypic.com/2924dq0.png
http://i47.tinypic.com/2w53rrl.png