Maybe its time for a better rating system. Instead of scoring a file just based on speed (three stars, four stars, etc) include with it an ability for users to downgrade the score if they find out its a virus, spyware or just a bad copy. You could allow only one 'vote' per IP as to deter one person skewing the rating too much. This could possibly help people filter out bad files when used in conjunction with the minimum rating feature. You might also do this by host, but that could be more complicated.