Win8 RTM- Desktop Still Shows in Alt-Tab After Closing

So, even after I close the desktop by dragging the window from the top of the screen, the desktop still shows in my alt-tab menu. If I alt-tab back to it, it's like it doesn't even realize it's open. I can't close it again, and about half the time it shows my wallpaper as a black background. The only way I'm able to close it again is by selecting the desktop icon from the Start Screen, or by pressing Win+D, the shortcut to open the desktop.

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(There's supposed to be a background here; you can see a thin line glimpse of it at the top of the screen.)

Anyone else having this issue? It seems like a relatively big thing to miss in the final release. (It also did this for me in the Release Preview, and I sent feedback to Microsoft to no avail).