BuddyPress.org

As hnla suggested, the topic is covered extensively on these forums. You can try a search using, ‘white screen’ (https://buddypress.org/search/?f=white+screen)

Before going too far, you might try to increase the php memory limit via the wp-config.php file first. If your host allows it, you can also change the setting in the .htaccess.

https://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP