BuddyPress.org

If you have other query_post loops running on the page, you might need to reset the loop.

Use something like wp_reset_query(); after a query_posts loop or use a WP_Query loop, which doesn’t require resetting altogether:
http://weblogtoolscollection.com/archives/2008/04/13/define-your-own-wordpress-loop-using-wp_query/