Perhaps cancel the file from download window, find it in incomplete folder in Library & select it, press Resume button.

Otherwise see http://www.gnutellaforums.com/downlo...wards-why.html

I also occasionally get corrupt files, usually video files. Sometimes the file will try to redownload the corrupt or missing parts several times & succeeds, sometimes it does not succeed. In those cases I cancel & try to find the file from a different source if possible. This is not always easy to do of course, might be some time after before I can find a different source or version of same file content.