I installed Lubuntu 18.10 overwriting everything on the drive. When the installation finished, I rebooted and logged in. I walked away for some time and when I came back this image was on the screen. Anyone know what it is or means?
Hitting a key cleared it and I saw the regular desk top and it seemed fully functional. The second time it happened I took a picture (figuring the printscreen key might clear the screen rather than capture it.) The vertical lines were moving in a wave pattern (the crooked vertical lines in the pic.) The flame pictured over the monitor didn't give me a good feeling.
At all other times since, leaving Lubuntu sit just brings up the default screen saver.