Alas! I discovered what the problem is...my router!
If you have a Linksys BESR41 router...don't use BitTorrent. Or Gnutella as an ultrapeer. Apparently, the firmware on this, and other products that have this chip in common, crash and burn when a large (>16) number of connections per IP address behind NAT are established. In other words. A very busy Torrent will bork your router, and the only way to fix this is to reboot it.
Thanks for that warning. I was about an hour into the download and didn't see any problem with my Linksys router, but why chance it?
In any case, I'm not convinced about bittorrent in general. With it I was averaging 60 kB/s download speed, now with regular 'ol ftp I'm getting 500 kB/s (from duke.) I really like the idea of bittorrent, especially helping out with bandwidth, but when I have to choose between 15 hour downloads (bittorrent's estimate) and 30 minutes (ncftp's estimate), there's not much to ponder.
Peter