I think I found something! I´m working with MacOS X Panther. Trying this and that I noticed, that everytime I started Limewire from the original Start button and leave it in the LW Folder, it worked. Having the folder closed and trying to open limewire from the alias in the dock, it disconnected the modem. Can that really be it? I tried it a couple of times and that´s how it always worked.