I have a similar problem. On my dial-up, reconnecting to the net fixes it. Obviously, this is not an usable solution for you.
Another thing: router.limewire.com and gnutellahosts.com, in my experience, do not have near as much reliability as another server that's larger than them. Try connecting to "gnutella.hostscache.com:6346". That particular one is usually my primary connection to GNet.

Kirby