Q. One of my devices ( Windows 2008 Server) is causing all the links and network ovals to disappear. When I monitor it with NT Services probe, every connection on the map disappears. If I select Host Resources, everything stays normal. I want to use only the NT Services probe for the servers on this map.

A. The SNMP probe (Host Resources) generated the network oval because it found a subnet there. Then, any NT Services probes attached themselves to it with the "guessed from address" fake interface. When you changed the last probe away from SNMP to NT Services, the network oval generated by the SNMP probe(s) becomes just a blank oval, because there's no longer anything about that network on the map, at which point all the other probes disconnect from that network oval because it is no longer the right subnet.

If you change the last device to NT Services, removes the blank oval and manually add a network oval with the right subnet, all of the NT Services probes should eventually attach themselves to it.