Shoutbox

The file you downloaded is still saved in a location called the 'cache'. If you choose to redownload it, it'll instead fetch the file from that cache because that is faster that redownloading it from the Internet again. Normally this would be fine, seeing as the file you want to download again is exactly the same one, from the same location. However, seeing as the file is corrupt it'll also give you the corrupt file from the cache again. To redownload it again from the Internet you should clear that cache. In Internet Explorer go to Tools > Internet options and click the button that says "Clear Files" (or similar wordings).

Additionally, using a mirror location should avoid this entire issue because it'll skip the cache (mirrors are located on another server).