Mouse-related + parent.
My sister bought my 92 (at the time) Mum a new notebook + wireless mouse. My Mum gets the tech - she just uses it to play patience - but not always the differences from when she did this on a desktop + wired mouse.
"My mouse is doing funny things....".
Looking at the screen, it was indeed behaving oddly, so asked for the mouse, which felt funny in my hand - big clue: as she was holding it upside down. Years of using a wired mouse had gotten her used to using the 'tail' to orient it - now she had lost the reference point....
I was sitting beside her when this happened - not sure how I'd've helped with this one over the phone!