I would be curious to know what happens if you do choose to browse hosts from that account to see if same problem happens.

Are these all Gnutella Network files? Or are some Torrent files?

Try this first, go to LW's preferences, Advanced, Performance & disable all options except for out of bounds searching. See if that makes any difference, if not then see below.

Make a note of all your important settings, then delete your LW preferences whilst LW is closed. Be sure to backup your Downloads.dat file, this is very important so you don't lose previous progress on incomplete downloads! Deleting LW Preferences folder in OSX
(note: deleting the LW preferences folder will also remove any LW custom descriptions you have given shared files.)

If this still does not work, could you report back the number of files in your incomplete folder, and how many shared files you have.

One thing I am wondering, if LW is frozen then the connection status might also become frozen. Do you lose internet connection at all? Do the browsers connect ok?