When LimeWire detects a file is corrupted, it will redownload the parts of the file that are corrupted. Current LimeWire versions detect this at the end of the download, and thus you can see, "Downloading -> Verifying -> Downloading -> Verifying", etc... up to 6 times, at which point if it's still corrupted, LimeWire will tell you so and ask you what you want to do. We're improving this for future versions so that as the download progresses, invalid chunks will be redownloaded (so you don't see the awkward redownload at the end) and to stop downloading from hosts who gave you the invalid data.