You may need to break up the delay. From a cold start, after the system has been OFF for some hours, the Marantz will probably be the slowest box to come online, but there are two stages to its startup. The first stage is power-up and being able to accept an input command and the second stage is a delay (usually in the 6-10 second range) before the audio amplifier is ready to go. Once the Marantz has accepted an input command, there will be an HDMI handshake with the input device and the Samsung display.
Each of these devices requires a certain amount of time to power-up and complete the HDMI handshake. If an impatient Samsung is ready to go before its input device is ready to engage in the HDMI handshake, the Samsung will throw the message.
In order to completely eliminate that message on a routine basis you may need to setup a dedicated "Start-Up" button that inserts the longest delays and sets all inputs and parameters (tone controls, default volume, surround mode, etc.). After Start-Up an abbreviated set of commands, probably without any delays, can be used to change inputs and control the devices.
You may need to turn things upside down and start the peripheral devices (Blu-ray, DirectTV, etc.) first, so that they are ready to engage in the HDMI handshake promptly when the Samsung asks.
If I'm setting up a system that includes unfamiliar (to me) devices, the customer will observe me apparently struggle as I endlessly issue commands, but I'm working out the minimum delays that I need for flawless operation. In one case with a really slow DVD player I needed a 30 second delay from a cold start. Without the 30 second user interface lockup, an impatient user would issue repeated commands that could end up with the system in an unexpected state and I'd likely get a call. With the 30 second delay there were zero calls, but I would hate to use the system because it started up so slowly. (customer's DVD choice, not mine)
Heads up: A future device firmware update may upset the optimum timing that you have worked out.
