I'm having the same problem - LW runs perfectly for a while, sometimes for ages, then completely drops the connection - confirmed when I then try to use Safari or Internet Explorer. I then have to restart my iMac completely to re-establish connection. (I'm not using a wireless network, but I think we may have the same issue)

I have a iMac G4, 256MB, BT Broadband, Zoom ADSL Modem and when it's working OK I'm currently sharing over 1000 files

Though not a devastating problem it is really annoying! Anyone got any ideas??