The first thing to try would be a new Java install but since he's only just done that... might not be much point

Try deleting the preferences folder, instructions here
Fixes for LimeWire
This will kill all of his settings within tools > options, so if he's not sure of his settings he should write them down (so that he can reset things afterwards). LW must be closed before deleting prefs. Also, it's a hidden folder, so he'll have to show hidden files & folders in order to see it!!

If that doesn't help, there's some more info here
http://www.gnutellaforums.com/showth...hlight=freezes