I have rarely the issue that all of a sudden, on some programs (for example Edge and Firefox) I can't see the top part of the Window anymore.

Preconditions for this to happen:

• Multi screen (does never happen on single screen setups)
• Happens only on the primary screen
• Only when application is maximised
• Only some applications are affected, not all (Microsoft Office apps are never affected): File Explorer, Edge, Firefox, Notepad and many others

What does not help:

• Minimizing and then maximizing the window again
• Closing the application and then starting it again

What helps:

• Press Shift-Ctrl-Win-B. This clears the screen buffer and solves the problem. But it might come back after some time. So this is not a permanent fix.
• Restart the computer (also not a permanent fix)
• Disable Protected Mode in Office (permanent fix, but makes Office less secure).

How to reproduce:

• Open a Word file in Protected Mode (e.g. a Word attachment in an Email will automatically be opened in Protected Mode)
• Then open an affected application (e.g. Edge) in a maximized window
• It will show with the top part not visible