Have same problem, except my isp is telewest.
Modem is a webstar that is supplied by telewest(broadband).
Have Bitdefender internet security, and have disabled firewall and still no luck. Unless I am unaware, I am not sharing my pc.

The error message I get on start up is:
Limewire was unable to set up a port to listen for incoming connections.

Please, any help welcome and I am sorry if you have gone through this before.

Thanks
gerrard8