Press Windows key + Esc first; this turns off Windows Magnifier, whose Lens view can appear as a transparent rectangular box on the screen.^1^
If the box disappears
Magnifier was active. To prevent it from returning automatically:
- Windows 11: Settings → Accessibility → Magnifier. Expand Magnifier, turn it off, and clear Start Magnifier before sign-in and Start Magnifier after sign-in.
- Windows 10: Settings → Ease of Access → Magnifier. Turn it off and clear both automatic-start options.^1^
If the box remains
- Test Narrator: Press Windows key + Ctrl + Enter once. Narrator can display a blue focus box around the currently selected item; the shortcut turns Narrator on or off.^2^ If that removes the box, press Windows key + Ctrl + N to open Narrator settings and turn off Use Narrator. Also disable its automatic-start options if selected.
- Reset the graphics display: Press Windows key + Ctrl + Shift + B. The screen may flicker and beep briefly. This safely resets the graphics driver and can clear a stuck transparent display artifact.^3^
- Identify a frozen application window:
- Press Ctrl + Shift + Esc to open Task Manager.
- On Processes, look under Apps.
- Right-click open apps one at a time and select End task.
- Stop when the box disappears; that identifies the responsible app.
- In Task Manager, open Startup apps, select that app, and choose Disable if the box returns whenever Windows starts.^4^
Ending a task closes that app, so save open work first.
If none of these changes the box, take a screenshot with Windows key + Shift + S. If the box appears in the screenshot, it is being drawn by Windows or an application; if it does not, check the monitor’s own on-screen controls for features such as a crosshair, focus frame, or picture-in-picture overlay.
References
- [Windows 11](https://support.microsoft.com/accessibility/windows/magnifier/chapter-1-introducing-magnifier#turn-magnifier-on-and-off)
- [Windows 11](https://support.microsoft.com/accessibility/windows/narrator/chapter-1-introducing-narrator)
- Troubleshooting black or blank screens in Windows
- How to remove a large black square from home screen - Microsoft Q&A