this is a server issue, the server is not properly configured to run php code.
as a test i created 2 files with identical code in them:
the code in both pages is very simple:
<?php phpinfo(); ?>
the phpinfo(); function should return information about the php server.
the phpinfo.htm page loads ok, and shows "hello world", the phpinfo.php page returns the 500 error. a properly configured server would not show an error for this simple code example, it would return the information about the php server. you will need to contact go daddy, show them the links t the 2 pages and the code being used in them. they will need to correct the problem.