blackath

ok i live in australia. i downloaded the game off steam, i waited and waited for it to finish then WOO it finished...but. when i launch it get all the way until 2 boxes are unticked then this message appears. Data file too short 'addons\dubbing.pbo'. Expected 1209930079 B, got 989593600 B. i mean is there some sort of patch, or something. please help me, i have no idea what to do and i really want to play the game. thankyou