I think it would be really helpful to include the corresponding file name in the "Expected part-hash ..." messages in the log. The way the setup is now, you just get a ton of these Expected/Actual part-hash messages and it's very tedious to figure out to which files they belong.
Since the messages always come in pairs, it's probably sufficient to only include the file name in the "Expected..." message and not the "Actual..." message. Plus, for long file names this would introduce less clutter.
So the messages could look something like this:
2005-11-06 13:39:08: Expected part-hash: ABCABCABCABCABCABCABCABCABCABCAB (File.I.am.downloading.zip)
2005-11-06 13:39:08: Actual part-hash: DFEDFEDFEDFEDFEDFEDSFEDFEDFEDFED