You are probably over cooking your cheese cake. Here are two things that you MUST do:

1. Obtain an instant read thermometer. Towards the end of the baking time insert the thermometer into the center of the cheese cake. Remove the cake from the oven when the thermometer registers 150 degrees.
2. As soon as you remove the cheese cake from the oven, run a thin knife around the cheese cake between the cake and the pan.

If you follow the above two steps, YOUR CHEESE CAKE WILL NOT CRACK.