check the upload speed, if you find your upload speed is greater than download speed, you can limit the uload speed for that torrent. In Transmission (the default torrent client in mint), double click on torrent to open properties and on the last tab, you can limit upload / down load speeds. There enable upload limit and set a values (I normally limit it to the current download speed I have).
Also if you are using mint6, you may have to open the port on which torrent client is listening. Just to ensure there is not port issues, if you are using transmission, on teh help menu, click on the fist item (some log..) and see the it says port is opened (you may have to go through lines of messges).
Don't fix it if it ain't broken, don't break it if you can't fix it -Husse