Same problem here, and I already tried everything from the "If LW will not connect"

1. OS version? Windows Vista Home Premium 32 bit
2. What firewalls you have? Only Windows'
3. How much ram? 4Gb
4. Hard Disk space available? About 190 Gb
5. Connection type? Broadband (5mbit)
6. Modem & router brand name & model numbers? D-Link DSL-2640B
7. Where are you trying to connect from? Home
8. What version of LimeWire (LW) & Java do you have? Limwire: 6.18.8
Java: The newest to date
9. Who is your ISP (Internet Service Provider)? GVT (Brazil)
10. 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? Your test worked
11. Are you sharing the connection with other computers or p2p sharing programs? If yes, please give details of set up. Another laptop using wireless internet
12. Is this a your 1st try at LW or is this a new problem with an experienced user. New problem with experience user
13. Do you see a brick wall in front of the blue world icon at the bottom of LW's interface? Yes
14. For those using a modem/router, how is your modem/router set up...are you port forwarding or is UPnP enabled? Port Forwarding
15. What security programs are you using (antivirus etc)? None
16. What country are you living in? Sometimes there are ISPs with the same name in more than one country. Brazil
17. Has anything in your setup changed recently? Have you updated your version of LW or Java? Have you added any new software or new hardware? Have you updated any software? Have you moved house, changed internet plan or ISP etc etc? Got a new laptop

Additional Info: this is my 4th day with the new computer and I've already managed to download something with FrostWire and even connected to the LimeWire network once, but ain't working anymore. Also, right in the beginning I uninstalled Norton 360 (which came from factory) and right after that I got a blue screen message, so I had to reboot from last known good config, which quite messed up things over here. But everything else is working fine, including games, MSN, etc... Oh yeah, and I've already port-forwarded, got a static IP, everything you can possibly think of! Windows Firewall is off.

Right now I'm going to test Ubuntu and try to install some P2P program on it.

As I make progress, if any, I will post it so maybe you can use it. I just don't know where to turn at the moment.