So you tried this one? DelinvFile - Utility for Deleting Invalid Files and Folders

'If' the download file is still in your downloads list in LW, then press the Cancel button. CLOSE LimeWire, (you will have to sacrifice your incomplete files to do this), delete your LW preferences Point #2 or most likely 3 in Fixes for Limewire (sample image included at bottom of page.) OR if VISTA see instructions for finding the folder here http://www.gnutellaforums.com/genera...der-vista.html & delete it. To double-check, go to your LW incomplete folder & remove any files called Downloads.dat or Downloads.bak

If that does not do the trick, then create a new folder, move all your good files to it, delete the entire folder where this 'rogue' file is. Then rename the folder you created to be exact to the older one & move it back. See if that works.