S.T.A.L.K.E.R. Call of Pripyat problems

[Crew08]

Hi
I have polish version of this game , version is 1.6.01
I using crack for German version and its working, but i have a few problems, and i dont know why. Because of this crack , i dont know.

Problems are with performance, game runs fine for some time and then i have problems wih fps, they dropping tro 10 fps and stays . I must save game, exit game and then load game and its fine for some time . Then its again.
Some problems with tasks. Sometimes in game is missing sound, this sound when we getting new task, or task complete , and without this sound i cannot complete tasks and main story, task dont wanna to complete .