I realize this is an old one, but I've experienced the same problem in recent versions as well. It appears that /requests/playlist.xml does not properly encode '&' characters (perhaps others too) causing an xml parsing error.
I can confirm this, if you have filenames with '&' in the name the playlist will not load because it is not & encoded, and this is why the webinterface is not displaying the current songname too.
a workaround would be to install apache, change the path in the .js file to the apache-server, and on-request (localhost:80/newplaylist.xml.php): load the playlist.xml from localhost:8080/requests/playlist.xml and replace &->&
OR:
change the functions.js to load the xml-file as textfile, replace &->& and parse the string as xml-file.