Lots of people are having problems with Tiscali all of a sudden. If you use the forum search to look for Tiscali, you'll find heaps of threads.
First of all, try changing ports...that fixed the prob for 1 lucky person
In LW go tools > options > advanced > firewall config. Change LW's listening port to one in the range of 49152 - 65535 (say 64049) > apply. Any ports forwarded thru a router must be the same number as LW's listening port!
Do you see the firewall icon (brick wall in front of the blue globe) & if so, has it always been there?
What's the brand & model of your router? Are you using it with UPnP enabled, ports forwarded or neither?