Have you configured your firewalls to allow LW full access?: http://www.limewire.com/english/content/firewalls.shtml

You could try these if you haven't already: Fixes for Limewire

Can you give us a total desciption of your set up: 1. OS version,
2. What firewalls you have,
3. ram, 4. HDD space available,
5. Connection type,
6. Modem & router brand name & model numbers,
7. Where are you trying to connect from (home, school, work, etc.)?