A page on how to disable them.
http://uk3.php.net/manual/en/securit....disabling.php
Which version of php are you using? In php 5 they are disabled by default, php 6 is not even going to support them.
If you're using php 4, then you should consider updating to 5 as 4 is only getting critical updates now, and will be fully dropped on 08/08/2008.