Erro:Warning: session_start() [function.session-start]:

[guaianet]

Instalei o joomla e quando fui no outro dia conectar no login adim, ta esse erro:
Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/raiz/public_html/configuration.php:54) in /home/raiz/public_html/libraries/joomla/session/session.php on line 413

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/raiz/public_html/configuration.php:54) in /home/raiz/public_html/libraries/joomla/session/session.php on line 413

Warning: Cannot modify header information - headers already sent by (output started at /home/raiz/public_html/configuration.php:54) in /home/raiz/public_html/libraries/joomla/session/session.php on line 416 E nao consigo logar.