After resaving all models and textures in game folder, one of the things i would try is to comment each line of code where you play sounds. I only once had this problem in my game (engine crash without any error message and without any warning) and i found after pain search that i simply put one line for playing sound on wrong place which causes crash. The only luck was that this was happening always and only in the same level, and it helped me a lot. Also with this you will check did you maybe have damaged sound file. In your case i don't think that problem is in damaged file, it should probably show engine error message but with this kind of crash you simply must eliminate this possibility.
Whether there is any previous indication that crash will happen, such as a sudden jump in consumption of memory in debug panel or something?