When the issue occurs, it's all my Explorer windows at once, not just one.
That's what happens with mine too. Earlier, most of us just report the window pop-up. That's because at first, we might just have 1 window open to begin with. But after a while, we will certainly see that however many explorer windows are in the background, they can/will all pop-up at once to the foreground.
After what i have seen, it has something to do with group policies. I have checked event viewer multiple times the moment the popup happens and i have always seen something with group policies be the newest events in event viewer. The worst part is, a computer checks for policy updates multiple times a day, even when the computer is not even connected to an AD server!