My wife has an HP laptop running windows 7. She has a very frustrating problem when typing: in some, but not all cases, typing the letter's "y" or "t" will cause the cursor to jump back a few lines or some number of words. The result is that she ends up typing over whatever it was that she was working on.

(as a matter of fact, I just experienced this while typing this question on her computer with the phrase: "typing the letter..." above.)

I've installed the latest drivers for her touchpad from Synaptic and disabled tap touching and gesture features to rule out simple unintended mouse clicks. Still the "y" and "t" keys continue to cause problems.