Access $vbulletin when in different directory

[myHybridcar.com]

I'm attempting to access $vbulletin when outside the forum directory. The following code works when the user is logged in, but for some reason if the user is not logged in the script starts outputting HTML as if I were loading a forum page. What's going on? Thanks

PHP Code:

    // check if logged in
    if (!$vbulletin)
    {
        $phrasegroups = array(); 
        $specialtemplates = array(); 
        $globaltemplates = array(); 
        $actiontemplates = array();
        $cwd = getcwd();
        chdir ('/home/myhybrid/www/forums/');
        require_once('./global.php');
        global $vbulletin;
        chdir ($cwd);
    }

    // if not logged in, show login form
    if (!$vbulletin->userinfo['userid'])
    {
    // show login form
    }