Weird nameless gray (or black) window appearing all the time

This started happening a few days ago. I'm not sure if it's related, but I uninstalled Acrobat DC and installed Acrobat XI and sometime after that it started. I get one of the following randomly in my Windows 10 desktop:
- "DDE Server" (or DDE Server Window, I'm not sure) which is an item in taskbar with a folder icon. You can't do anything with this, it just appears there.
- A totally gray window (1/4 size of the screen) with a white top. You can't do anything with this except you probably can quit it with alt+F4. This window has no name, no ID of any kind. It does NOT appear in NirSoft's WinList and AutoHotkey barely recognizes it as "ahk_class WorkerW" and "ahk_exe Explorer.EXE".
- A totally gray or black box which covers a part of everything (sitting on top layer). Nothing can be done to this, not even alt+F4 works.
- I also got weird problems with browsers: mouse cursor is not pointing to the place that it should (it is off a bit). Or a black bar was on top of browser, offsetting the real content.

I know this probably sounds like my OS it totally messed up. But I don't think so, something is just very buggy. I don't think I have a virus, at least Windows defender doesn't find one. I just updated BIOS after the problem started and Windows Updates are all up to date.

How do I figure out what is launching the annoying box? It just randomly appears maybe 1 minute after restarting Windows.

There seems to be something invisible also on top of the screen so that on certain parts of the screen I can't click anything because the invisible thing is preventing that. It seems like there are multiple instances of the invisible boxes (because I can click in between of them).

When the black annyoing box appears, if I try to click that, the Windows 10 Asterisk error sound plays. Nothing else happens, nothing can be done to that box. AutoHotkey doesn't recognize that window (no information) and it's not possible to focus mouse/keyboard on that black box.

Now I was able to find out that WinLister indeed does help me with this. I can see that the black box matches with several open windows. I can do the matching by comparing window location and sizes. So what are these windows? It's a long list at the moment:

• Class: WorkerW
• DDE Server Window (Class: OleDdeWndClass)
• Class: Base_PowerMessageWindow
• Class: Chrome_WidgetWin_0
• Logitech SetPoint
• Default IME
• MSCTFIME UI

So it's pretty much random. Those windows have clearly "crashed" to a buggy state. But naturally the source of the problem is probably not those applications. Although DDE Server Window is the most prominent one so that maybe the suspect #1.

I also noticed that when the problem appears, then right-click-on-desktop and Intel Graphics Settings do work, but Display Settings and Personalize do nothing (they don't open and there's no error message). That suggests this might possibly have something to do with multiple displays crashing somehow. I have two screens, a TV and a projector. Never had a problem like this before, it just suddenly started and I didn't do any changes to the screens. I do not use an extended desktop or anything like that, just one desktop multiplied into two screens.

"Intel Graphics Settings do work, but Display Settings and Personalize do nothing (they don't open and there's no error message)."

It sounds like a command prompt window initiated by something (not likely Acrobat). I would try uninstall graphics driver in Device Manager, restart and let Windows install something it's happy with, as a start.

If it persists, I would do a Repair Install, using Option 4 ISO file, vs spending hrs trying to debug this. It would take less than 2 hrs, keep your files and programs intact and leave you with a clean system (watch included video, if you're uncertain) - Repair Install Windows 10 with an In-place Upgrade

Thank you mrgeek, these sound like very valid suggestions. Actually, the black box size is very similar to a cmd box size. However, it is slightly smaller. But could very well still be it.

Right now I've got the box there again. Now it's totally white. This time Display Settings open up just fine, so apparently they are not hand-in-hand every time. I'll try your suggestions.

Thank you mrgeek, these sound like very valid suggestions. Actually, the black box size is very similar to a cmd box size. However, it is slightly smaller. But could very well still be it. The buggy window size is always 986x528px (position 52x101px), according to WinLister. Right now I've got the box there again. On last reboot it was totally white and now it's invisible. This time Display Settings open up just fine and also uninstalling the graphics driver (and it installed the same again) didn't help.

I did also sfc /scannow in cmd.exe and it went through and said this:

"Windows Resource Protection found corrupt files and successfully repairedthem. Details are included in the CBS.Log windir\Logs\CBS\CBS.log."

That log had many lines saying "Primitive installers committed for repair" at the time of running sfc. Now I reboot and if the problem comes back, I guess I have to Repair Install.

Now I got a smaller white box on a different position on the screen. WinLister said it was TeamViewer. These symptoms are giving me some physical damage vibes. If Repair Install doesn't help, then I need to find out what component is broken. This is Intel NUC6i5SYK.

I have now done the Repair Install utilizing Media Creation Tool and running setup.exe from Win10. It didn't work out. The end result is Windows 10 desktop is totally black, only cursor is visible. Shift+ctrl+Esc or Win+P don't bring anything on the screen. Only the cursor is there. I can do ctrl+alt+del to restart or change user, but also my other user has the exact same black screen only. Right now on the screen there is a window "Personalized settings" and that has been sitting there for 3 hours.

What is very notable is that when some spring update or something appeared maybe 6 months ago, the OS forced installing that. So it installed and that also resulted in the exact same black screen problem. At that time my solution was to System Restore to the previous point and I then tried to disable forced updates. But it updated again later on. But then it worked fine for many months. But now, after the USB in-place-upgrade it's the black screen again.

I can invoke Safe mode but it's the same thing in Safe mode, the black screen only.

So I bet I could probably System Restore again to some previous point. But it seems now I either have 1) black screen problem or 2) appearing invisible/white/gray box problem. What do you suggest I should try next?

You have tried the usual steps; Win+p and change users. Did you try to create a New User which would make fresh profile ?
Next and easy thing to try is hard power off the computer with the power button, wait a minute, then power back on. The Windows setup may just not have finished or been interrupted.
If this doesn't change anything, it's a graphics or display issue. Do Win+P, arrow up or down one or two, press Enter to see is wrong display is issue. Though you can't see it, the menu is there, we need to get to top of list option- main monitor.
If that doesn't work, in Safe Mode which you say you can get to, uninstall the display driver completely and restart.
Lastly, try a Repair or older System Restore from the Advanced options in Troubleshoot.