Sound loss after MCE idle overnight/long time

My W7MCE PC ceases driving Samsung TV speakers after a "rest" period.

The PC is only used for TV/PVR Plex work. About a week ago we noticed the issue (although wife says it has happened a couple of times before but very very infrequently )
Only MSoft security updates have recently been applied to system.

At the end of the evening having watched Live TV, I normally press stop on remote control and leave MCE showing guide. TV screen is then switched off.

In the morning I power on TV screen and once the MCE guide is showing I press Live TV on remote control. The picture appears but no sound.
Checking control panel sound shows HDMI connection active and green sound bar moving.
If I turn MCE sound to minimum I get subtitles which suggests to me that Windows is producing audio stream.
Logging off from Windows and logging on again clears problem.
I have checked "services" and Windows audio is set to start "automatic"
The only thing I can think of doing is to system restore back to an earlier date.

Any other suggestions would be welcome.
Thanks
Mike

The sound, via HDMI, in most cases is generated internally in the Video card. In some very old systems, the HDMI audio is generated by the S/PDIF connection on the motherboard to the video card. The PC's audio (e.g. Realtek) is not used for HDMI audio. It sounds like possibly a power setting(?) or maybe a video driver? Just guessing as no hardware info was provided. One other thought, with the TV powered off Windows may have detected no HDMI and switched back to the "Speakers" (PC sound card) and the reason there is no audio? Next time it happens look at the Sound Panel/Playback section and see what is set as default audio playback device. If that is the case all you have to do is reselect HDMI audio as the default audio playback device and you should have sound again instead of a reboot.

There are additional settings within a power plan. Look at those. I use my PC for general PC work and internet but I also use it for my Recording Studio so I have the Power Plan set to High Performance. The only thing I do is "power off" the monitor after a designated time, nothing else. I have an SSD drive, not a mechanical hard drive.

Tried High Power setting but problem still exists. Opening volume mixer from task bar shows Samsung HDMI device active with sound being delivered by WMC application. Restored PC back to 1/8/2017 and still have problem. Next step is to replace TV and see if that is the problem

That was a thought as it still seems to be a "power" issue and something is turning off after a period of inactivity or the remote HDMI device being off.

Sounds like you got it sorted out. Since it worked OK at one time, have you tried "reseating" the video card? (with the PC powered off, remove the card then reinstall). I would also install the latest video card drivers.

Jack