I fixed it on my site. You just must make sure you open up the correct line to edit.
Example:
Warning: Cannot modify header information – headers already sent by (output started at /var/www/vhosts/phattkicks.com/httpdocs/wp-includes/class.wp-scripts.php:54) in /var/www/vhosts/phattkicks.com/httpdocs/wp-includes/pluggable.php on line 711
The error of the ?> space is on line 54, not 711 where it sounds like it is.