Constant crashing.

It doesnt seem to matter if it's trees or stone. the entire game just stops, everything freezes and when I go to do anyhting the game just shuts itself down. I just paid $70 for this game and have had nothing but problems since I installed it. This Really needs to be fixed. I can get 5 seconds into the game and it will freeze then crash. I have tried everything I can think of to fix it to no avail.