It is most likely your video card or RAM not able to process and buffer fast enough. Try setting all Vide stuff to loest settigns afrom options panel and then play and see what happens. Also double ot triple you Ram Swap file setting in control planel - this game needs video grunt and lots of it.
If these still don't fix the prob - then very likely you are having a conflict of some type.
Make sure you have latest hardware drivers, virus checkers, and garbage cleaners in place
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