-opening Host Mon and making all changes
-closing HostMon a message appears like "... host monitoring will be terminated."
What means "opening Host Mon"? Looks like you start another instance of application. You don't need to do that. When HostMonitor running as service it displays icon in system tray. You may click the icon and configure HostMonitor.
If you do not see icon, there are can be several reasons:
1) "Icon in system tray" option (located on Preferences page in the Options dialog) is disabled.
2) Service started under user account instead of "local system" account (use standard "Services" application, "Service Properties" dialog to check this)
3) Option "allow service interact with desktop" is disabled (use standard "Services" application, "Service Properties" dialog to check this)
4) You use Terminal Service to connect to remote system where HostMonitor is running. Icon is not visible because service can interact with local desktop only. In this case to change HostMonitor's settings follow these steps: stop HostMonitor's service, start HostMonitor as regular application, change settings, close application, start HostMonitor as service again.
Regards
Alex