resuming torrent from different site/tracker

[the_dude]

Hi, I've got a really annoying problem. Not sure if it's normal or not though.

I've download around 50% of a torrent from a private tracker. I've decided to stop the download and resume downloading it from another private tracker.

I simply deleted the torrent from the utorrent list and loaded up the new torrent file (public trackers allow you to "load" a different tracker into the same torrent but this doesn't work with private trackers; with private a new torrent is created in utorrent rather than combining them. So I just deleted the old one entirely and added the new one).

It begins the checking process and this is where the problem arises. It never actually detects the full percentage that was download. I previously download 50% but after "checking" when using the new tracker it only reaches around 35% and begins downloading. This is especially a problem cause it's a very large torrent (>10GB)

Why does this happen? Any help appreciated

[DreadWingKnight]

Differences in piece sizes are the first cause.

Piece offset changes caused by extra files can also cause it.