Changing Screen Options for Marketpress Products Page

When we changed the screen options on the products page to show more than 200 items, we got the following error: Fatal error: Out of memory (allocated 52166656) (tried to allocate 16 bytes) in /homepages/44/d359197309/htdocs/wordpress/wp-includes/wp-db.php on line 1449

How can we fix it so that we can view our products page?