Hello, I am receiving this same error message. I'm using:
wp version 3.5.1
seo plugin version 1.3.4.4
I'm currently using the Zenon Lite Theme.
Error Message:
Warning: Cannot modify header information - headers already sent by (output started at D:\Hosting\2930673\html\wordpress\wp-includes\script-loader.php:710) inD:\Hosting\2930673\html\wordpress\wp-includes\pluggable.php on line 876
The plugin still installs and seems fine, but when I go to edit a page, the drop down window is unresponsive, it will not expand to offer the programing options.