I had one of my more tech-savvy users look at it, and he fixed it by changing the php in 'holdsession.php' from
PHP Code:
echo "<meta http-equiv=\"refresh\" content=\"$secs; URL=\"$vboptions[bburl]/holdsession.php$session[sessionurl_q]act=arcade&do=play&gameid=$gameid\">";
to
PHP Code:
echo '<meta http-equiv=\'refresh\' content=\'' . $secs . '; URL=' . $vbulletin->options['bburl'] . '/holdsession.php' . $vbulletin->session->vars['sessionurl_q'] . 'act=arcade&do=play&gameid=' . $gameid . '\'>';
AND changing
PHP Code:
$session['sessionurl_q'] = "?$session[sessionurl]";
to
PHP Code:
$session['sessionurl_q'] = '?'.vbulletin->session->vars['sessionurl_q'];