I have tried all the suggestions, nothing worked.
Since purchasing the LW pro for my daughters laptop 2+ months ago it has never connected.
here are the system details I have:-

1. OS version? Windows Vista, Administrator
2. What firewalls you have? norton
3. How much ram? 2gb
4. Hard Disk space available? 200gb
5. Connection type? broadband
6. Modem & router brand name & model numbers? echolife HG520s
7. Where are you trying to connect . house
8. What version 4.18.3pro java 1.6.0_07
9. Who is your ISP talktalk
10. Do this simple test for us. didn't work
11. Are you sharing the connection None
12. Is this a your 1st try at LW . use an older version on another computer at home and it works fine.
13. Do you see a brick wall in front of the blue world icon ? yes
14. For those using a modem/router, how is your modem/router set up...are you port forwarding or is UPnP enabled? dont understand?
15. What security programs are you using (antivirus etc)? norton 360
16. What country are you living in? UK.
17. Has anything in your setup changed recently? LW has not connected since it was purchased and loaded.

I'm sure it's something easy to fix, but we can't do it without help.
regards,
emma

Try changing port numbers. Make sure that LW on this computer isn't using the same listening port as LW on the other computer.
Then, delete LW's preferences folder (make sure LW's properly closed before you delete the prefs folder). There are instructions for both in this thread: If LW Will Not Connect

Also, try removing the LW rules from Norton's firewall & adding them again. Check out this link: http://www.gnutellaforums.com/226610-post6.html

Since you can use LW on one of your computers, hopefully changing ports etc will do the trick!
TalkTalk are known for causing problems for LW users. If you use the forum search to look for TalkTalk, you'll find quite a few threads

Otherwise, try the rest of the fixes in the 'If LW Nill Not Connect' thread.

If you're still stuck, try enabling UPnP in the router (have a look at the router's manual & there should be instructions). Then in LW go tools > options > advanced > firewall config. Use the UPnP option > apply > ok. Restart LW & see if it connects.

If nothing's working, post back & I'll give you instructions for port forwarding.