header already sent multidomains

Hi !

Still issue

[Thu Jul 21 11:25:15 2011] [error] [client 41.250.153.243] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/mgr/public_html/wp-content/mu-plugins/multi-domains.php:1163) in /home/mgr/public_html/wp-includes/pluggable.php on line 739, referer: http://mejmar.org/wp-admin/themes.php

on mapped or multidomained sites....