How to prevent UNWANTED change from INSERT to OVERTYPE ?

[Sebastian42]

INSERT often changes to OVERTYPE 'by itself'. It happens in a DOS text program, in Notepad and in modern chat programs which I run in 32bit Win10 pro v1809. I have cleaned the keyboard, swapped keyboards and disabled the INSERT key (with Sharpkeys) - all to no avail. I can rule out the accidental pressing of the keypad's INSERT key, when I mean to press the right arrow because I physically removed that INSERT key. I suspect that there is a hotkey combination for OVERTYPE which I accidentally activate - but have no idea what it might be.