Hi there
My "Group E-mail Subscription" plugin conflicts (500 server error in front-end and back-end) while updating to Buddypress 1.5.3
see http://buddypress.org/community/groups/installing-buddypress/forum/topic/internal-server-error-after-upgrade-to-1-5-3-1/?#post-120148
Greets from the Netherlands
http://wordpress.org/extend/plugins/buddypress-group-email-subscription/