Open the incomplete folder, open the file in question & see if it opens ok. If it's a media file, see if it plays to the end. If it does, then cancel the download, remove file from incomplete folder, rename it removing the number at beginning of it.
Other than that, keep searching for new sources to download from. Only other thought is ...
http://www.gnutellaforums.com/downlo...wards-why.html