To solve this issue, reboot the host computer. If this fails to resolve the issue, re-install the host while physically sitting at the host computer.

You may see this message in Rescue when the computer you are connecting to goes into a mode which cannot be accessed while Rescue is running as an application. Example of this would be if the computer is set to lock itself after a certain period of inactivity. You can prevent this by running Rescue as a system service, which is an option you initiate directly before clicking Launch Remote Control.