q & a page title is broken it displays broken core.php

core.php is broken in the q&a plugin,

<br />
<b>Warning</b>:  call_user_func_array() [<a href='function.call-user-func-array'>function.call-user-func-array</a>]: First argument is expected to be a valid callback, 'QA_Core::wp_title' was given in <b>/home3/polished/public_html/wp-includes/plugin.php</b> on line <b>199</b><br />

any idea how to fix?