There are fake files throughout the network. Typically, these have large numbers of sources (though sometimes they'll also show up with a few sources only) & will sit connecting for ages, then get stuck needing sources forever. What type of files are you searching for?? For music files, try using the 'All Types' search, search for album or artist rather than song title & go for a file with around 10 sources.
For video files, always check the file with Bitzi before download. If a file has heaps of sources but no Bitzi rating, chances are it's a fake.
Check out these threads for more info & tips, including how to use Bitzi
Fake files showing up in search results How to find music (also tips for video)