The machine selection dialog consists of two lists. The one on the left is used to select the machine on the network you wish to diagnose. If your network has more than one zone, there will also be a zone list for selecting the proper zone.
The list on the right is used for selecting the Alert! Network Responder. Since this is a very new type of background application, it is likely you will not see anything else in this list. The list is provided for future compatibility when other types of responders become available.
