Suggestion: Group Calendar - Check if BuddyPress is Active

Suggest that you add a check into the BuddyPress Group Calendar to verify that BuddyPress is active. If you have the Calendar plugin activated, but deactivate BuddyPress for any reason (such as upgrading it), you will white screen your WP.

Here are the directions:
http://codex.buddypress.org/how-to-guides/checking-buddypress-is-active/