I, like you, am experiencing almost the identical issue. My laptop is working fine on 4.12. I loaded 4.18 today on the desktop (haven't used it in just over one year); using my verizon wireless connection (on both the laptop and desktop). I've followed all the tips that Limewire has offerered and to no avail. I even tried to turn off my firewall. I'm not a cg but smart enough to follow directions to troubleshoot. I am at a loss. Please if you figure this out, let me know.
Oh, same system, same service pack, same one bar turning green. Ugh. For what it is worth, my laptop has Vista (ugh again).
Many thanks,
Carlene