I also have been unable to connect to the network. This has just happened recently. I have been using Limewire Pro v 4.12.11 for some time without any problem. my operating system is windows XP and I have a broadband connection and plenty of disk space. I use PC tools firewall and have disabled the windows firewall. Limewire was an exception in both. I have also disabled both without effect.
Only thing I can think of is maybe a problem with internet explorer 7.
Anyone got any ideas

Try deleting LW's preference folder with LW completely shut down. Instructions in this thread points 2 & 3(check both locations): Fixes for Limewire(try the other fixes too). This will reset all your option settings, so make a note of them first(if you can).

Also try uninstalling and deleting all versions of java from your Add or Remove Programs Control Panel. Then d/load and install Java Runtime Environment 5.0 Update 12, use the offline installer.

If that fails, post your details: System details - help us to help you -> Provide these details when you post!!!

__________________
If it ain't broke, fix it till it is!

I tried all of the above without success. I uninstalled limewire and installed frostwire which gave the same problem. Chat room works OK. I tried it just to be sure. Also managed part of a video from the frostwire network. It seems as though I just cannot conect to the P2P network. I also uninstalled Internet explorer 7.0 as this has caused me problems in the past.

System details
OS Windows XP
FW PCTools
HD Space 105 Gb free
Broadband connection
Version was Limewire Pro 4.12.11
Java 1.6.0_02
ISP Tiscali
Test worked
Connection not shared
Firewall icon is visible at bottom of page
AVG antivirus
live in UK.
Grateful for any advice