I'm running Limewire 1.4 with Mac OS 9.0.4 on a G4 with a modem connection, and I rarely have problems within the first half hour or so of starting up. Early on I learned that I had to limit my upload slots or the bandwidth I've allocated (50%) would quickly come to a grinding halt. I've set simultaneous uploads to 3 and max uploads per person to 10, and this seems to work reasonably on my system at least for a time.

After a half hour the strange phenomena I alluded to may start occuring. On the monito tab I find more than 3 uploads in progress after pressing "clear inactive". If I come back any amount of time later, those same uploads are still listed with no further % progress indicated. If I kill those uploads, I never see any new uploads take the freed up slots. Downloads still functon successfully while this is happening, but uploads are effectively crippled. This has occurred several times to me this week.