I am in "Prelude to Maelstrom" in "The World Eater's Eyrie" where two portcullises are operated by three stones and a lever. The problem is that the middle stone does not move and, no matter what the two outer stones are set to, the portcullises never open. I have tried every cobination of the two outer stones, including the solution in the offial game guide. As a computer programmer myself, I went through some of the basic bug clearing steps... I have tried loading an earlier save. I have restarted my xbox. I have exited and reentered the building to reload the map. Nothing has worked. I am trapped and unable to complete the main quest.

Any help you could offer would be greatly appreciated.