Were you able to connect before that 2 weeks?

Did you enable UPnP on your modem/router? If your device doesn't support UPnP then port forwarding is the way to go. Instructions for these here, check the whole page Connection problems? Check here first! (click on link)

Did you disable XP's firewall? And you saw this Configuring Norton Internet Security

Can you give us a total description of your set up:
1. OS version? (eg: Windows 98)
2. What firewalls you have?
3. How much ram?
4. Hard Disk space available?
5. Connection type? (eg: dialup, broadband, cable, etc.)
6. Modem & router brand name & model numbers?
7. Where are you trying to connect from (home, school, work, etc.)?
8. What version of Limewire (LW) & Java do you have? (Go to LW's menu Help>About LW...) Will show both LW & Java version.
9. Who is your isp provider (Internet Service Provider)?
10. Are you sharing the connection with other computers or p2p sharing programs? If yes, please give details of set up.
11. Do this simple test for us. Using your browser go here: http://www3.limewire.com:6346/ The page should say 'Your test worked!'. What happens when you go there?
12. Is this a your 1st try at LW or is this a new problem with an experienced user.