BuddyPress.org

Hi

I just installed WPMU + Buddypress, and I keep getting the following error message:

Warning: session_start() [function.session-start]: Cannot send session cookie – headers already sent by (output started at /home/hatemon/public_html/wp-content/mu-plugins/bp-groups/bp-groups-ajax.php:1) in /home/hatemon/public_html/wp-content/mu-plugins/bp-core.php on line 153

Warning: session_start() [function.session-start]: Cannot send session cache limiter – headers already sent (output started at /home/hatemon/public_html/wp-content/mu-plugins/bp-groups/bp-groups-ajax.php:1) in /home/hatemon/public_html/wp-content/mu-plugins/bp-core.php on line 153

I use WordPress MU 2.6.5.

The first time the error appeared was right after I uploaded the BuddyPress package.

Can someone tell me what to do? Please Thanks!