My friend trying to create an acct but had a trouble.

I was trying to invite him, I got this error on the "invite a friend" window:

Warning: file_put_contents(/web/sites/jmedia/bearzone.com/plugins/htmlpurifier/standalone/HTMLPurifier/DefinitionCache/Serializer/HTML/4.1.0,0fa6f510f367da3a203a9d2abb02f1b6,1.ser) [function.file-put-contents]: failed to open stream: Permission denied in /web/sites/jmedia/bearzone.com/plugins/htmlpurifier/HTMLPurifier.standalone.php on line 11157

Warning : Cannot modify header information - headers already sent by (output started at /web/sites/jmedia/bearzone.com/plugins/htmlpurifier/HTMLPurifier.standalone.php:11157) in /web/sites/jmedia/bearzone.com/inc/design.inc.php on line 133

I wish I could understand the error here.

Result: Email Sent Failed

Anyone know how to invite a friend?