Warning : session_start

Hi,

I have a problem on my web site with modx.
I work on mac and when that I try to reach the web site with a Windows navigator I have this problem

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/sites/site63/web/modx-2.0.6-pl/index.php(1) : eval()'d code:7) in /home/sites/site63/web/modx-2.0.6-pl/core/model/modx/modx.class.php on line 2842

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/sites/site63/web/modx-2.0.6-pl/index.php(1) : eval()'d code:7) in /home/sites/site63/web/modx-2.0.6-pl/core/model/modx/modx.class.php on line 2842



Pls help me, It is the first time that I have this problem

A plugin you have in your MODX site is likely triggering an error and sending output before the session is being started. Try disabling any plugins that might be firing on events that occur early in the request process and this should go away...