I had the same problem in the council chamber - I switched to software mode and 600x800 resolution, it was BIG and very FAST <img src="/ubbthreads/images/graemlins/puppyeyes.gif" alt="" />, but I could finish the chamber without any more problems, then I just reset the settings to normal Direct 3D.

Hope you can use it, bye!

...Carry on, into the horizon, wielding courage, staff in hand, journey through the shadows and dreams and what lies beyond the guardian's keep...