wp version 3.5.1
seo plugin version 1.3.4.4
error message received :
Warning: Cannot modify header information - headers already sent by (output started at /home/property/domains/pgpropertyagent.com/public_html/wp-admin/includes/template.php:1642) in /home/property/domains/pgpropertyagent.com/public_html/wp-includes/pluggable.php on line 876