session problem

[eluser]xaero[/eluser]
I have problem with sessions.

in autoload.php I set the following settings:

$autoload['libraries'] = array('database','session');

in routes.php I defined default controller:

$route['default_controller'] = "main";

And codeigniter displays the following error:

Code:

A PHP Error was encountered

Severity: Warning

Message: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at Z:\home\vcms\www\system\application\controllers\main.php:1)

Filename: libraries/Session.php

Line Number: 141

I use the rewrited session library.