Need help solve this problem

I have guestbook 2.2, I have done something, can't remember what, this is the message I am getting when I log into admin.
The guest book works, but I can't get rid of these annoying messages, grateful for any help.
TBH.

Warning: Cannot modify header information - headers already sent by (output started at /home/swefil9/public_html/guest/admin/config.inc.php:57) in /home/swefil9/public_html/guest/lib/admin.class.php on line 65

Warning: Cannot modify header information - headers already sent by (output started at /home/swefil9/public_html/guest/admin/config.inc.php:57) in /home/swefil9/public_html/guest/lib/admin.class.php on line 67

Warning: Cannot modify header information - headers already sent by (output started at /home/swefil9/public_html/guest/admin/config.inc.php:57) in /home/swefil9/public_html/guest/lib/admin.class.php on line 69

Warning: Cannot modify header information - headers already sent by (output started at /home/swefil9/public_html/guest/admin/config.inc.php:57) in /home/swefil9/public_html/guest/lib/admin.class.php on line 71

is one of the most common errors in PHP. It happens when the script goes to send the header to set the cookie but some information has already been sent to the browser. I would need to see the page to be more accurate but it could be anything, even just a space.

the page is at

http://www.swefil.com/guest/admin.php

temporary login:
user: swejan
pass: wizbin

Is it also possible to update to adv.guestbook 2.31

TBH
JE

You are using version 2.2 of the guestbook so I don't need a password to login as it has a nice exploit that lets me login.

Anyway back to the problem. You must of editted a file somewhere. Something in the admin/config.inc.php I am guessing. Looking at the code it's just empty space or possibly soe new lines but no text.

I had the same problem and removing everything after the last ?> in admin/config.inc.php solved it.