m17 R4, black lines appear on screen any time display turns off

I've started experiencing a problem with my m17 R4. I noticed a few black lines along the bottom of the screen, which extend about half way across the screen, before starting to fade out. I've attached some photos that show this behavior.

Important details:

• The lines do not show up in screenshots or video capture. So, if I do any kind of screen capture, the lines won't be there. It seems to be an artifact of the display/screen itself.
• Once the lines show up, rebooting the computer won't get rid of the lines.
• The lines are visible before Windows begins to boot. If I press F12 during startup, and run the pre-boot diagnostics, the lines are visible on that screen. It's not possible to determine whether the lines are visible on the BIOS screen itself, because the content of the BIOS screen has a black margin along the bottom that extends into the area where the lines would appear.
• There's a very reliable way to get the lines to appear: Any time the display turns off (Edit Power Plans -> Turn off the display), the lines will appear the next time the display turns back on.
  • However, there are a number of things that do NOT cause the lines to appear, assuming they weren't already present. As long as the lines aren't there, I can shut down, power up, restart, sleep, or hibernate the system without causing the lines to appear. It seems to be almost exclusively the action triggered by "Turn off the display" that causes the lines to appear.
• There's a very reliable way to get the lines to disappear again after they appear: Open GeForce Experience, go to Drivers, and choose "... -> Reinstall Drivers". This takes several minutes, but towards the end of the installation the screen will blink off and on again briefly. When that happens, the lines will go away. I haven't found any other way to get the lines to go away.
• To attempt to troubleshoot this, I've updated to the latest Windows Update, applied all SupportAssist updates, and applied the latest BIOS update. None have had any impact on the problem.

At this point, although I'm able to temporarily get rid of the lines by reinstalling the graphics drivers, my concern is that this indicates a hardware issue that will only get worse.

Below are several photos that show the lines along the bottom of the screen.

Beyond the center of the screen, the lines fade out completely. They don't go all the way to the right edge of the screen.Closer to the center of the screen, the lines begin to fade out.The lines are very sharp and noticeable along the bottom of the screen.

The lines are visible even in the pre-boot test.