Heaps of people have had probs with Tiscali lately.
Some people have found changing ports helps. To do this, in LW go tools > options > advanced > firewall config. There you can change LW's listening port. Good ones to try are 49152 - 65535. Someone recently got connected after weeks of pain using port 139. Have a read of these...

Tiscali & Limewire
can't connect between 5pm-11pm
I have found a solution to getting Limewire to work with Tiscali

Use the forum search to look for Tiscali, you'll find lots more threads

If you do change ports, you'll have to also change your port forwarding for the new port number.
You've got a firewall problem somewhere, so double check your Windows firewall config & also your port forwarding setup. Did you set up a static IP address before port forwarding? Remember that LW's listening port, port in the 'manual port forward' box & port forwarded within a router must all be the same number.