The problem is that when uTorrent seems to have finished it's download, my unpacking software doesn't unpack it because one/more piece seems to be corrupted. Well, after re-checking with uTorrent, it now says it has been downloaded some 99,4%. I used Azureus before and changed to uTorrent because of similar problems. The problem is that sometimes I can unpack the file I've downloaded, but it seems to be corrupted, and doesn't work 1OO%.
The problem still occurs after reinstalling windows and changing the target hard drive. Sometimes the downloads say 1OO% and stays so after re-checking, but the unpacking software seems to think some pieces are corrupted. This happens quite often and I don't do anything different when unpacking/downloading. So it ain't any random error user might execute.
I dont know why it is doing that, could it be that the site you are downloading from is bogus!!! Try and check the comments if any whether others are having the same problem as you.