Hm, if you are familiar with networking you can try and use WireShark and diagnose what is happening at which layer. I don't know how well it interfaces with GunZ and the log-on, GunZ in general, or how to troubleshoot this problem. I understand the concepts, but, haven't used it.
If you want to try that method and create a dump or something of results I can try and diagnose it with no guarantee.
