Windows 11 Mystery faint box in Win 11

[sidr]

Win11 works fine for a day or so, then it becomes unstable, with a mystery faint box in lower centre of screen (refer 2 attached).
I also have a video clip showing this, but it is 15MB and this forum doesn't seem to allow it to be added (if someone provides an email address I can send it).
If I move the mouse over this box, the mouse changes to a blue spinning circle.
If I move mouse away from the box, the mouse returns to normal white arrow.
The only way I can remove this box is and instability is to reboot twice, then mystery box disappears.
I have tried
-MS Trouble shooter
-“Admin Prompt” - sfc /scannow
-Checked drivers are up to date
Any solution?

 

[davehc]

Something is trying to load /install. Have a look at your startup list and see if you can identify anything unusual.

 

[sidr]

Something is trying to load /install. Have a look at your startup list and see if you can identify anything unusual.

While waiting I did some googling and found
www.systreat.com/how-to-fix-floating-transparent-box-above-the-taskbar-on-windows-11/
"Fix 3":
Ctrl-Alt-Del, Task Manager, Processes, right-click on Windows-Explorer, Restart
This worked, in terms of removing the mystery box. But it doesn't stop it coming back every 1-2 days.

I looked at startup list, and should I delete:
-twdsuilaunch
-cortana
-helpviewer
-realtek hd audio universal service

 

[davehc]

I would delete all of them, except cortana, but you may be running software for which I am not familiar. But disable them for a stater, reboot and see what happens

 

[Neemobeer]

It is most likely some malfunctioning process. You can try the following

1. Download ProcExp from Microsoft
2. Launch process explorer
3. Press and hold the mouse on the crosshair icon and try hovering over that window
4. If it highlights then release the mouse click
5. Process Explorer should then highlight which process it is

From there you should be able to determine your next course of action

 

[sidr]

Thanks. I just got more unrelated instability, so I have rebooted. I will have to wait a day or so, to have the mystery box re-appear before I retry.