On my PHPBB forum i found following errors at /ucp.php?mode=register

Deprecated: Assigning the return value of new by reference is deprecated in /home/*/public_html/forum/includes/captcha/plugins/phpbb_captcha_qa_plugin.php on line 104
[phpBB Debug] PHP Notice: in file /includes/functions.php on line 4584: Cannot modify header information - headers already sent by (output started at /includes/captcha/plugins/phpbb_captcha_qa_plugin.php:104)
[phpBB Debug] PHP Notice: in file /includes/functions.php on line 4586: Cannot modify header information - headers already sent by (output started at /includes/captcha/plugins/phpbb_captcha_qa_plugin.php:104)
[phpBB Debug] PHP Notice: in file /includes/functions.php on line 4587: Cannot modify header information - headers already sent by (output started at /includes/captcha/plugins/phpbb_captcha_qa_plugin.php:104)
[phpBB Debug] PHP Notice: in file /includes/functions.php on line 4588: Cannot modify header information - headers already sent by (output started at /includes/captcha/plugins/phpbb_captcha_qa_plugin.php:104)
in /home/*/public_html/forum/includes/captcha/plugins/phpbb_captcha_qa_plugin.php on line 104 was:

Code:
        function &get_instance()
        {
                $instance =& new phpbb_captcha_qa();

                return $instance;
        }
i turned "=&" into "=" and after page refresh, the errors was away.