New Installation sessions.php on line 67 error

[kartooz]

OK ADMIN could you please help me out. i made four attemped to install this on my server. i had installed and worked on numerous website. i am having this problem first time. rather then installing over and over could you please tell me why i am having this session error.

$key=$kv['key']; if (gettype($this->$key)!="user function") $this->$key=$kv['value']; } } } ?>
Warning: session_start(): Cannot send session cookie - headers already sent by (output started at /home/www/cellularclinic.com/includes/classes/navigation_history.php:143) in /home/www/cellularclinic.com/includes/functions/sessions.php on line 67

Warning: session_start(): Cannot send session cache limiter - headers already sent (output started at /home/www/cellularclinic.com/includes/classes/navigation_history.php:143) in /home/www/cellularclinic.com/includes/functions/sessions.php on line 67

check website at www.cellularclinic.com