You mentioned this is also happening on your laptop running uTorrent. Does this mean you are running ABC on a different computer?
If both computers are on the same network, try taking your laptop and heading to a wireless hotspot or different network and download a torrent from there, and see if you get the same problem. If you don't, chances are your ISP or something on your network is messing with your torrent data (which would mean you are probably also sending bad data), and forcing encryption may help. I'm not sure if ABC has this feature, but uTorrent definitely does. It might also be something on your computer, but it would have to somehow be on both computers. If you want to check, borrow a friend's laptop and start up a torrent on it, but to be safe, don't log in to the BBT site.
Just to check, is this happening with torrents you get from other sites?