This kinda hits home with me, because due to a mistake in reassembly after cleaning only my down-arrow key registers with the slightest of touch. All the other keys require a good hard press to register, but I cannot touch the down arrow lightly enough while still feeling it without it scrolling things down. So often my tendency to rest my finger between all the arrow keys when using them will result in scrolling down right after I've scrolled up.
that awkward moment when you don't know if its appropriate to point out her breasts are on her keyboard or not.
Lightly put you hand on her shoulder and tell her to lean back. She will probably do just that, thinking that you want to reach the keyboard better. Without doing anything else you say that the problem is solved and seeing as the scrolling will have stopped she will probably realise on her own.