I've figured out what the problem is--this particular file was created with Azureus, and it looks like Azureus did something weird in that one specific instance. The "dht_backup_enable" item in the "azureus_properties" part of the torrent should be an integer, but is instead a string (containing the value "1").
A *second* problem is that Azureus reads the file enough to cache its own internal copy of the .torrent file, which will keep the error coming back, even if you fix the file.
Look in your Azureus cache (...wherever Azureus keeps stuff on your system.../active/) for a file called 3938659FE003D69303ADFCB4E7774BB9A5193B0F.dat (and possibly that same name .dat.bak) You'll need to delete this file before continuing. You should probably shut down Azureus, then delete this file, then start back up again.
Once you've done that, you can load a repaired .torrent file into Azureus (my version is attached here as .torrent.txt, to get past the attachment filters--sorry), and all should be well. Because the change is outside of the info section of the .torrent, it doesn't change the tracker signature, and all continues to work as expected. I might ask that someone from L-E upload my repaired version (or repair the file themselves) to .torrent sources (I got mine from scarywater), since this problem is going to hit any user of a recent Azureus version--and the workaround (as you see above) isn't trivial.
Thanks.
(Edit: Oh, and I found the torrent going with 11 peers and no seeds--everbody was almost almost almost done, too. Happily seeding away, now.)
