Can;t access forums or admincp after move to new host
 

We get this error:
Unable to add cookies, header already sent.
File: /home/content/html/online/includes/config.php
line: 1

after move to new host.
I made all required changes to config.php
DBname dbuser etc
i tried disabling hooks and even the path above in the forum path variable.
i reuploaded a working config.php to and made changes again to make sure i hadn't left any whitespace. Anyone know what else do do?