Problem with my Trainz after downloading.

To fix the locos having problems when you rotate around them go to the trainz launcher,then choose options,once the options menu opens go to the "tuning settings" tab,locate "train poly count". Bring that slider all the way to the right. Now launch the game and try again...:)
part of the problem may have to do with your computer itself and how much of a poly load it can handle.