It might be linked to the same type of issue I had where Sassan could not summon the demon. If it is then a patch is on the way. The guys said there was a problem with over all Play & Pause time adding up to cause this as they were set to time calculations or something like that. They said it was linked to only a few scenes so it could be one you have found.
Here is the topic:
XBOX 360: Sassan can't summon demon.If you look on the later pages you will see messages from posters with
Larian Studios under their names. These may help answer your questions for the time being until they reply to you.
Here is a quote below from Lar_q from that topic,
"
For the more technically inclined - the core issue (and why we never encountered it) had to do with how the game represented time. Time is stored in what is known as a floating point format and the numerical precision of the format we used tends to decrease at the time values become larger. If by the time you get to this particular scene, time was sufficiently large, calculations done on time could give wrong results that propagated through the code, and caused this particular scene to lock up. The issue was further obfuscated because only a few scenes depend on this particular time calculations, so people in quality assurance never found it because they tend to go through the game as fast as they can, and even if they had the issue, they didn't necessarily run into scenes that had this problem."
