There's another fairly current thread on precisely this already. In that case the Superhub was in modem mode making it a little puzzling as apparently the only change was from a modem to the Superhub with the same router.
In your case I'd guess that the most likely problem is the number of connections you are running your client on is exceeding the internal connection table in the hub and causing it to hang. Look in the torrent client settings and reduce the maximum connections. I can't suggest a number as I don't run either torrents or the Superhub but I'd suggest even the Superhub must be able to cope with a hundred or so connections.
Other thread -
http://www.cableforum.co.uk/board/12...ing-modem.html