There is a warning about session_start() whenever I call the session_start() function.

Example:
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /www/99k.org/t/e/c/techz/htdocs/index.php:2) in /www/99k.org/t/e/c/techz/htdocs/index.php on line 3

How can I eliminate this warning since .htaccess file cannot be used in Zymic ?