Hi, it seems than there is a conflic with an other plugin for BP, called “Buddypress Notifications Manager”
The following alert is displayed:
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/…/wp-content/plugins/buddypress-notifications-manager/loader.php:117) in /home/…/wp-content/plugins/buddypress-media/app/main/controllers/media/RTMediaViewCount.php on line 20
I can’t give you more info about it, sorry but if you need more, then I 'll do it
PS: nothing is uploaded from activity wall (all is right with profil uploader)