Thread:Project:Support desk/cannot modify header information - headers already sent in webresponse.php-line 38

I am using a SMW extension, the code is as follows I am getting the following warning 4 times Cannot modify header information - headers already sent by (output started at /serverlocation/filename.php:1) in /serverlocation/includes/WebResponse.php on line 38 can some one help me out? what is the reason behind this