It's possible the files you are downloading are corrupt to begin with... that happens a lot with peer-to-peer downloading. Also, there could be an issue with you ISP; I know that a long time ago, it would often take multiple attempts to download almost any file, because the download would start and then almost immediately I'd get the message that the download was complete. Obviously, a 5MB file doesn't download within one minute on dial-up. You might be having a similar issue.