During game play I have a very different error then a CTD

While playing the game My fps will drop to about ~4 then I will get the following error message

"Music error: cannot create filter graph" the game will save automaticly and then it CTD's however when I start the game again my save is titiled restore, and it saved the game right before it crashed.

This error occurs only when you are playing the game and it occurs at any random time, but on the average I can onyl get about 10-15 minutes of uninterupted play before it happens.

If any one can help I would greatly appreciate it.