Either a file permission problem has happened or the path to the files has been corrupted. It is imperative you run the game consistently under Vista. Example, you cannot rn the game using "Run as Administrator" one time and not the next time. Vista uses two different paths to the game files when you do that.
Next, you should not be running Norton under Vista. There are serious issues with Norton and Vista that cannot be worked around.
Also, you cannot install the game as one user and run it as another user without loosing your configuration settings in the game due to how Vista alters the paths of the game config files.
It could also be a simple matter of the files being write-protected, which is usually due to some security program, like Norton.
Now, if you are saying the head position will not change when you press the arrow keys (not on the number pad), then that is an entirely different matter.
