Yeah it does that.
I think it's a cookie path problem, because when I changed the php to include the cookie path in domarkallread.php like the other cookies are set, it worked on the board I help with.
I changed:
setcookie("{$config['cookieprefix']}w3t_visit",${$config['cookieprefix']."w3t_visit"},0);
to
setcookie("{$config['cookieprefix']}w3t_visit",${$config['cookieprefix']."w3t_visit"},0,$config['cookiepath']);