In your main application, whenever the state changes and you need to make it available to the user, then simply update the Text property of the notify icon, then when the user moves over the icon is the task tray then the tooltip with the text will be displayed. This is consistent behaviour with windows applications and therefore does not annoy the user.
You could also change the icon on a state change.
notifyIcon1.Text = "The New State";
notifyIcon1.Icon = .........;