The torrent tracker file stops downloading or the movie itself? Lately, I've been seeing a lot of the tracker files stopping mid way through download (they less than 100Kilobytes) so that I have to go to a different torrent site to find the file. It has happened from a few torrent sites linked from torrentz.com including pirate bay.
If the movie itself is being blocked then your isp might be blocking torrent traffic. Who is your isp by the way?