Don't know if this is old news (ain't trawling thru this thread to find out), but this is what fixed it for me - had tried all the other stuff, disabling autoconnect, deleting /.limewire etc., none of that worked. What I did:

- Tools
- Options
- Advanced
- Firewall Config
- select 'Do Nothing' (Router configuration)

Restart - Limewire will now work.

When restarted, go through the above steps and this time reselect 'Use UPnP'.

It continued to work after that.

Hope that helps some of you.