Three computer Windows home network, two of which (#1 and #2) are XP and one Windows 7, and all of which have VirusScan Plus. All three were trusted on the McAfee network manager. #1 and #2 could see each other. However, the other XP (#3) could see #1 and #2, but could neither be seen nor pinged by #1 or #2.. By chance, after a huge time investment, I changed the trust status of #1 and #2 on #3's McAfee to untrusted. Since then, #1 and #2 have had no trouble seeing or pinging #3.
Probably This situation may occur when the primary or authoritative system is reinstalled or When the re-installation is performed, network management data is lost . The loss of management control prevents you from making any changes to managed or unmanaged devices on the network, and from monitoring the status of those devices from the authoritative computer .