I'm running out of ideas...
You could try uninstalling Limewire using the uninstaller which is found in start > all programs > limewire...then re-install it using the offline installer...To find the offline installer, use the link below > cancel the installer window when it pop's up and then select the offline installer link...
Lime Wire ยป Download LimeWire
If that doesn't help could you goggle your modem and see what info you come up with regarding port forwarding...I couldn't find anything...