Same problem here.
I am using Limewire 4.10.5 Pro, Java 1.5.0_06, Windows XP, broadband cable.
If I leave the computer unattended, after a couple of hours, there would be an error message saying that I don't seem to have an internet connection (when it is not so) and my LW would show that it's disconnected. My Norton System Doctor dashboard would be showing 100% CPU activity.