Fatal Error is getting fatally aggravated!

Keep getting this message everytime I activate marketpress.

Fatal error: Out of memory (allocated 54001664) (tried to allocate 30720 bytes) in /public_html/wp-admin/includes/update.php on line 49

I have 512M of server RAM. I added php.ini to the home/public_html/wp-admin/wp-contents/wp-includes

Added
define(‘WP_MEMORY_LIMIT’, ‘512M’); //to wp-config.php after <?php

I changed wp-inludes/default-constants.php

// set memory limits
if ( !defined(‘WP_MEMORY_LIMIT’) ) {
if( is_multisite() ) {
define(‘WP_MEMORY_LIMIT’, ‘512M’);
} else {
define(‘WP_MEMORY_LIMIT’, ‘512M’);
}
}

if ( ! defined( ‘WP_MAX_MEMORY_LIMIT’ ) ) {
define( ‘WP_MAX_MEMORY_LIMIT’, ‘512M’ );
}

With 512M and 1.5G Burstable RAM

This shouldn’t be an issue. I logged in to the WHM and ran a memory trace and the server memory consumption was only 32%.

Using wordpress 3.4.2 single install

I only have all the newest versions of buddypress, cubepoints, cubepoints-buddypress, cubepoints login widget, adminbar customizer, adminbar minimizer and the custom community theme activated. AND THATS ALL!

Please help I can’t resolve this issue.