You need to configure your firewalls to allow LimeWire full access both TCP and UDP. Instructions can be found here. http://www.limewire.com/english/content/firewalls.shtml

If this doesn't help provide the following information:

Computer type and CPU
Operating System and sp (MAC,Win98)
LimeWire Version
Java Version
Firewalls
Modem type and model no.
Router type and model no.

Thank you