How do you install the game?
Do you use the small or the full install?
I had this problem with the small installation too, because of my CD Drive. He always have to read fast data out, and so it comes.
Or my defrag your harddrive, when your files are spilt up in hundered pieces it isnt good either
I dont know if you can choose a full installtion at your version. In the German version you havent this option free, and he is always play all data from CD.
The best way is then, to copy all data to the Grim directory and use a no cd crack, of course use this method only if you have trouble with the game, not too crack it!