I few times recently I've had a torrent at 99% with only a few pieces remaining. When I look at the pieces tab they are in and endless loop of being "repaired". If I quit tixati and delete the incomplete pieces then start up again they are downloaded normally. But until I notice it uses infinite bandwidth just re-downloading the same pieces over and over.

Maybe peers sending bad data during the repair process aren't being ignored as they would be when sending full pieces. Or there is something wrong with the repair algorithm. Just guessing.