You might want to check this:
http://www.gnutellaforums.com/showth...t=Cant+Connect
And this:
http://www.gnutellaforums.com/showth...t&pagenumber=2

If you are using Limewire at a company, school or university it is possible that the administrator has disallowed Gnutella to use certain ports like 6346, if this is the case you have to try to connect to non 6346, you can usually find some of nodes to connect to using GWebcache.