Ok so I'm at the ending of the quest when you're in the Falmer dungeon with Karliah and Bryrnjolf (think I spelled one of those wrong) after you become a Nightingale, and when you open the door to the last place when you're about to fight Mercer. After Mercer sais "you can't get the drop on me", and the ledge collapses and you're standing at the bottom, Mercer just stands there with my controls disabled and the game failes to execute the next part. (PC version, w/mods)