linux / cre loaded / php - troubleshooting

or webshop on a Hetzner Server is making problems. the server hosts 5 websites. we are getting the following error trying to access the CRE LOADED admin panel: Warning: Cannot modify header information - headers already sent by (output started at /var/www/web4/web/admin/includes/languages/polish/[login to view URL]) in /var/www/web4/web/admin/includes/functions/[login to view URL] on line 57 we do not know what is causing the problem. please get our webshop up and running again. could be linux permissions, or ISPConfig (web admin panel), etc. a skilled person should be able to fix this quickly.