http://imgur.com/EErL1lZ
I've been getting these errors on torrents randomly for a while now. Sometimes a torrent will be perfectly fine and download without a problem, but other times it will start downloading and then stop after this error notification pops up. Re-downloading the torrent will sometimes fix the issue, but not always. It'll download for a while and then the error will pop up. This torrent in the image for example got to 50% before there was an issue.
Any ideas what might be wrong?