Warning: Cannot modify header information - headers already sent by (output star

I have a couple installations where I can not create a new sign up. When I try I get the following error: Warning: Cannot modify header information - headers already sent by (output started at /home/content/h/s/u/hsuso/html/wp-content/themes/bp_social112/bp-social/header.php:2) in /home/content/h/s/u/hsuso/html/wp-includes/pluggable.php on line 868

I've deactivated ALL plugins with the exception of buddypress.

My website is http://iawov.com

My other two installations are working fine so not sure what happend here.