Try the advice here: all of a sudden will not connect (a fix to try)
Read that thread carefully
Start off by deleting LW's preferences folder when LW's properly closed. You'll know if you've deleted that folder properly...when you start LW, you'll go through the setup wizard again.Were you able to conect ok before using the Java 1.6.0_03?

If nothing there helps, please give us your details.
System details - help us to help you -> Provide these details when you post!!!

When LW was connecting properly, did you see the firewall icon (brick wall inn front of the blue earth)? if so, you could try port forwarding for the Linksys. The instructions are here.
Port Forwarding for the Linksys WRT300N
Don't forget to set up a staic IP addess first, or port forwarding won't work.
LW's listening port, port in the 'manual port forward' box & port forwarded within the router should all be the same number.