Are you sure the files aren't already corrupted? If it's files of your own or from someone you trust, that's one thing. But if you're grabbing file from others, e.g., video content via torrents, it's next to impossible to tell if it's you or the file. Heck, it might even be dummy files from the MPAA meant to frustrate ppl just like yourself.
If possible, try downloading some files you KNOW are good, maybe from a friend, before committing to all this effort regarding your network. It might be perfectly fine.