error message top and bottom of page

hi people,
this is the first time using opencart so please bare with me.
i have performed a clean version of opencart v1.4.9.3
everything seemed to go ok, iv deleted the install folder but have this error message at the very top of the page,

Warning: session_start() [function.session-start]: open(/var/tmp/sess_b50e64a927e6c82c8a66d33db766fce3, O_RDWR) failed: Permission denied (13) in /home/d/w/dwclothinguk/public_html/system/library/session.php on line 11Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/d/w/dwclothinguk/public_html/index.php:92) in /home/d/w/dwclothinguk/public_html/system/library/session.php on line 11

and this error at the very bottom of the page

Fatal error: Call to a member function get() on a non-object in /home/d/w/dwclothinguk/public_html/index.php on line 91

these came up

These errors show up in firefox but in IE the page loads fine but with errors on it.
in firefox i cannot access the admin page as i get this error

Warning: session_start() [function.session-start]: open(/var/tmp/sess_b50e64a927e6c82c8a66d33db766fce3, O_RDWR) failed: Permission denied (13) in /home/d/w/dwclothinguk/public_html/system/library/session.php on line 11Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/d/w/dwclothinguk/public_html/admin/index.php:72) in /home/d/w/dwclothinguk/public_html/system/library/session.php on line 11Warning: Cannot modify header information - headers already sent by (output started at /home/d/w/dwclothinguk/public_html/admin/index.php:72) in /home/d/w/dwclothinguk/public_html/system/engine/controller.php on line 27
Fatal error: Call to a member function get() on a non-object in /home/d/w/dwclothinguk/public_html/admin/index.php on line 71

but in IE i can get to the admin page and edit but again it has errors.

I have tried deleting everything and reinstalling but i get the same error



any help is appreciated

Documentation on: Headers already send

Thanks I'll have a read and report back

ok strange thing happened. i left the site for a couple of days and it appears to have fixed itself. is that even possible?
i havent touched it and now all seems fine.