Firefox+zone alarm ed errori visualizzazione

[alva]

ciao a tutti, ultimamente con l'ultima versione di zone alarm security suite, navigando sul sito snowfriends.it, nella pagina dei messaggi privati, quando aperta mi compaiono queste scritte di errore che allungano di molto la pagina web, sopra ai messaggi che comunque riesco a leggere:

Warning: Cannot modify header information - headers already sent by (output started at /web/htdocs/www.snowfriends.it/home/themes/Sunset/theme.php:140) in /web/htdocs/www.snowfriends.it/home/includes/sessions.php on line 249

Warning: Cannot modify header information - headers already sent by (ou started at /web/htdocs/www.snowfriends.it/home/themes/Sunset/theme.php:140) in /web/htdocs/www.snowfriends.it/home/includes/sessions.php on line 250

Warning: Cannot modify header information - headers already sent by (output started at /web/htdocs/www.snowfriends.it/home/themes/Sunset/theme.php:140) in /web/htdocs/www.snowfriends.it/home/includes/page_header.php on line 525

Warning: Cannot modify header information - headers already sent by (output started at /web/htdocs/www.snowfriends.it/home/themes/Sunset/theme.php:140) in /web/htdocs/www.snowfriends.it/home/includes/page_header.php on line 531

Warning: Cannot modify header information - headers already sent by (output started at /web/htdocs/www.snowfriends.it/home/themes/Sunset/theme.php:140) in /web/htdocs/www.snowfriends.it/home/includes/page_header.php on line 532


anche in homepage nel box dei messaggi istantanei quando ne scrivo uno mi esce la scritta seguente al posto del box, una volta ricaricata la pagina torna tutto a posto. il sito è in PHP-Nuke



Warning: Cannot modify header information - headers already sent by (output started at /web/htdocs/www.snowfriends.it/home/themes/Sunset/theme.php:142) in /web/htdocs/www.snowfriends.it/home/blocks/block-ShoutBlock.php on line 212


come risolvo? devo settare qualcosa in zone alarm?
Grazie