Why or how do torrents "lose" pieces?

I seed many torrent files and often one or more of them will "lose" pieces - usually off the front and back when looking at the Pieces column of the "Files" tab on Utorrent. These are my files; they were 100% at one time - then I end up having to download pieces from the cloud to make them... show more I seed many torrent files and often one or more of them will "lose" pieces - usually off the front and back when looking at the Pieces column of the "Files" tab on Utorrent. These are my files; they were 100% at one time - then I end up having to download pieces from the cloud to make them complete again!

What's up with that?!
1 answer 1