I've found an interaction between the BigContact and Ultimate TinyMCE plugins. When I use their advance HTML editor, I get this error:
Warning: Cannot modify header information - headers already sent by (output started at /home/christia/public_html/awdol-test.com/wp-content/plugins/ultimate-tinymce/addons/codemagic/codemagic.php:5) in /home/christia/public_html/awdol-test.com/wp-content/plugins/bigcontact/BigContact.php on line 44
Not sure if this is due to bigcontact not being compatible with WP 3.5. Any help would be appreciated.