Obviously these aren't subject to copyright or you have the copyright holder's permission, because you are discussing this on a public forum.
Some p2p software is better than others.
Kazzaa doesn't seem to resume downloads very well, often leading to a few bytes corruption.
Try emule or bit torrent clients, these will provide you with a faithful file copy.
If the original at the other end(s) has bad frames, you'll get them too.
Try divxdigest or doom9 for more info in restoring or hiding bad frames.