The gnutella.net file is inside the LimeWire preferences folder & should be deleted for LW 5 as this seems best for LW 5 & it will create a new one. Since you have already deleted the 'old' LW preferences folder once, it will now be called Limewire, not
.limewire
Image sample
http://www.gnutellaforums.com/window...tml#post183932 
Of course this needs to be done whilst LW is closed.