I've noticed that Gnotella appears to get stuck when connecting to some IPs (Connections panel). The status changes to "Connecting", but the connection never completes. In most cases, Gnotella will drop the attempt and try a new IP, but in some cases, the IP appears to sit in the list, blocking attempts on other IP addresses.

Would a list of problem IP addresses be helpful? Is there other information I should be looking for to help you track this down? It is definitely not a global problem with Gnotella, as sometimes one address will connect quickly even while another address appears to be stuck.