I just found this: <?php ini_set("memory_limit","64M"); ?> which I placed at the top of my page and received the following error:
Warning: Cannot modify header information - headers already sent by (output started at /Applications/MAMP/htdocs/dogPedic_Contest/users_Registration.php:5) in /Applications/MAMP/htdocs/dogPedic_Contest/users_Registration.php on line 27
This was on my MAMP testing server.