Desktop Image Resizes to Unusable Small Size

Twice now within a month, I keyed a key, and my desktop image resized itself. I see on my screen an image of the deskstop maybe a third the size of the screen at the center of the screen. The remainder of the screen contains nothing and is black. I can see two icons of my desktop and part of the task bar. The icons look magnified. I can move the mouse only in the upper half of the left half of the screen where there has been nothing that I could click. In this state, the system is unusable.

Nothing happens when I try to right click on the desktop.

The windows button continues to function, and I can open the Start Menu. I have been able most of the time to shut down the system.

I started in safe mode, and everything looked fine. When I restarted normally, I had the same problem.

On restart at the log in screen, I saw the word "Windows" centered in the image. The restart image looked like it had been designed that way.

It looks like Windows is trying to display a desktop landscape image for a mobile device. I haven't found a way to do that or to undo it.

To get my system back, I restored a checkpoint from a few days previous.

I have run my malware software, and it found nothing.

Windows Update is working on my system.

Windows Explorer does crash frequently on my system.

I have looked and havn't found this exact problem by anyone else.

Does anyone have any idea of what is happening?

I should have added that I saw a title bar at the top of the image. The image had a title bar and task bar with start button.

I also should have added that I have a Dell D830 laptop, not a desktop unit.

I also use 150% font magnification. Could that be why the mouse working area was less than the screen image?

What I saw looked like Windows thought I had a small phone display but was using my large screen resolution settings to display the image and showing only a fraction of it.

Welcome to the Forum.

If it works fine on safe mode, it can be the graphics driver. Did this happened after a update?
Under safe mode, try to see if there is a restore point before the issue began.