Thanks, I just turn off multicore proc and the the hitching stopped.
Looks like possible bad programming by Valve .
Finished the all the SP campaigns and its still short...once you get into a routine it becomes vary easy. Boy it was tough because of the hitching and freezes. It would have been impossible to play online MP with the probms. Maybe I will get online later...but the the idea of killing zombies get old fast for me...but thats just me. Just doesnt get exciting when there is nobody shooting back.
Boy one to two more years before CoD6 modern.