CB seem to use a deprecated call-time pass-by-reference. This should be fixed, because it's often set to off by newer php versions and hosting providers.

PHP Warning: Call-time pass-by-reference has been deprecated; If you would like to pass it by reference, modify the declaration of array_unshift(). If you would like to enable call-time pass-by-reference, you can set allow_call_time_pass_reference to true in your INI file in /xxx/joomla15/administrator/components/com_comprofiler/library/cb/cb.session.php on line 41