Hello!! I'm having the same problem... It happens occasionally and don't know how to keep this from happening... I was able to get on with no problem in the past now as of today LW will not connect!!!! Here is what I have on my system..

1. OS version? (eg: Windows 98) If using Windows Vista, please tell us whether you have an Administrator user account. WINDOWS XP
2. What firewalls you have? WINDOWS LIVE ONECARE
3. How much ram? 2048 MB DDR DUAL CHANNEL
4. Hard Disk space available? 320 GB
5. Connection type? (eg: dialup, broadband, cable, etc.) BROADBRAND
6. Modem & router brand name & model numbers? DSL MODEM ACTIONTEC BY QWEST MODEL #GT701
7. Where are you trying to connect from (house, appartment complex, school, student accomodation, work, etc.)? HOUSE
8. What version of LimeWire (LW) & Java do you have? (Go to LW's menu Help>About LW...) Will show both LW & Java version. LIMEWIRE 4.18.3 PRO JAVA 1.6.0_7
9. Who is your ISP (Internet Service Provider)?
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? IT SAID: "YOUR TEST WORKED"
11. Are you sharing the connection with other computers or p2p sharing programs? If yes, please give details of set up.
12. Is this a your 1st try at LW or is this a new problem with an experienced user. THIS IS THE 3RD TIME IT HAPPENED
13. Do you see a brick wall in front of the blue world icon at the bottom of LW's interface? _ click here to see Sample image always do and its worked just sometimes when I get on it doesn't want to connect
14. For those using a modem/router, how is your modem/router set up...are you port forwarding or is UPnP enabled? UPNP IS ENABLED
15. What security programs are you using (antivirus etc)? Some people might not be aware that their security suite includes a firewall
16. What country are you living in? Sometimes there are ISPs with the same name in more than one country (eg Clearwire in the USA & also in Ireland living in Phoenix, AZ