At the moment there is a huge amount of faked files hosted on the network. Those are mostly files of popular artists hosted by people or groups trying to discourage P2P client users from downloading such files.
From what you said I understand that you can download certain files and others you can't. That means that you neither have a firewall problem nor a corruption problem of the LW preference folder (though trying to delete the latter one as described in Point #2 & 3 in Fixes for Limewire might have some effect on your problem:
http://www.gnutellaforums.com/showth...threadid=36420
As for searching. You should rather search files under "All Types" using the artist's name or the name of an album. From the search results you can then browse the hosts and see whether they offer the specific files you're after. Choosing files with a smaller number of hosts (i.e. 5-15) might also prevent you from connecting to such faked files. Searching at different times (i.e.morning, afternoon, evening) can also bring up different results.
