Go to the Connections window & how many ultrapeers are you connected to? Or how many are stable? The beta has an ip blacklist, perhaps that has helped to block out some fake ultrapeers (UP's). Sometimes closing & re-opening can bring some fresh UP's.

Perhaps Brad.G's point about UPnP being unreliable also fits for your model. It's probably a later model with later version firmware. But as suggested earlier, one range of the linksys models have major firmware problems. (any model with 54 in its model name but especially the WRT54G is a "lemon") And generally port forwarding is more reliable than UPnP. Though in most Linksys devices the UPnP support is very good. Also, a reboot of the linksys might help. Or just a cold start after turning it off for 10 mins or so.

(BTW the LW beta has bit torrent support!) http://www.limewire.com/english/cont..._history.shtml