I've noticed this intermittently under the circumstance that the G2 host cache is empty and Shareaza 2.7.4.0 is told to connect to G2. Often it will "just work" but sometimes it seems to get stuck in a loop where:
1. Every few seconds, it says it is querying a discovery service (in blue in the network tab)
2. At least half the time, it's the same damn one (named "BROADCAST")
3. It doesn't actually connect to any G2 hubs, or even seem to try (no G2 items in the upper pane of the network tab, not even in gray). Instead it seems to query each discovery service, ignore whatever it returned, wait a while, and then repeat, which is obviously not correct behavior.
This looping issue seems to eventually spontaneously resolve itself; after a while it doesn't ignore the discovery service it just queried and starts trying to connect to the hubs it reported instead. I haven't found any way to speed up the process and kick it out of this loop sooner when it gets stuck in it. There's no obvious reason why it should start trying to connect to fresh G2 hubs within seconds sometimes, but spend several minutes spinning some wheels and not doing anything else first other times. Clearly, though, it would be far preferable for it to exhibit the reasonably-quick-connect behavior consistently and the looping-for-a-while-seemingly-doing-nothing-at-first behavior never.