today I have open my vps error log and I saw that was full of errors like:

[05-Oct-2014 21:26:02 Europe/Rome] PHP Fatal error:  Call to a member function getId() on a non-object in /home/cenex/public_html/ow_plugins/mailbox/controllers/ajax.php on line 111

Line 111 is this:

if ( !OW::getAuthorization()->isUserAuthorized($user->getId(), 'mailbox', 'reply_to_chat_message') )

can you help me to resolve this issue?

Thank you