When you use the OfficeScan agent uninstallation program to remove the OfficeScan agent program from endpoints, the program automatically notifies the server. When the server receives this notification, it removes the OfficeScan agent icon in the agent tree to show that the agent does not exist anymore.
However, if you use other methods to remove the OfficeScan agent, such as reformatting the endpoint hard drive or deleting the OfficeScan agent files manually, OfficeScan will not be aware of the removal and it will display the OfficeScan agent as inactive. If a user unloads or disables the OfficeScan agent for an extended period of time, the server also displays the OfficeScan agent as inactive.
To have the agent tree display active agents only, configure OfficeScan to automatically remove inactive agents from the agent tree.