There are lots of fake files on the network now. These will sit connecting for ages & then get stuck needing sources forever. They won't ever download. If some songs download fine, your LW's ok.
Try searching again, use the All Types search & look for artist or album rather than song title. Go for files with 10 sources or less, or files with a modem source. Check out the links below for more info & tips

Fake files showing up in search results
How to find music