External Display Disconnect/Connect Sound after Inactivity

I am using an Inspiron 15 - 7591, with Intel UHD Graphics 630. I have an external display connected to the HDMI 2.0 port, set to extend the display. Whenever the computer powers down the displays due to inactivity, Windows 10 makes the disconnect hardware and connect hardware sounds 2-6 times. Upon moving the mouse to awaken the computer, any windows that were open on the external display have moved to the internal display. The external display shows the desktop wallpaper. I can then manually drag the windows back over.

I used the program EventGhost and it shows:

System.DeviceRemoved [u'\\\\?\\DISPLAY..........
and then
System.DeviceAttached [u'\\\\?\\DISPLAY..........

so I believe the computer loses its connection with the monitor when it tells it to power down.

I tried another display with its own HDMI cable and experienced the same problem. I'm using the latest Intel graphics drivers from the Dell Support website. Any suggestions for fixing this annoyance would be appreciated. 

John B