Moving Joomla problems

[Shought]

Hi guys,

 

I have moved my Joomla site and re-uploaded it however I am not getting the error.

 

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/username/public_html/index.php:2) in /home/username/public_html/libraries/joomla/session/session.php on line 3
Duplicate entry '' for key 'PRIMARY' SQL=INSERT INTO `wk1gz_session` (`session_id`, `client_id`, `time`) VALUES ('', 0, '1367502648')

 

I have tried googling however found the only thing is to put session_start (); at the top of the session.php however this still has not worked.

 

Please can someone assist with this?