According to HP's spec, your machine has a "Touch Pad with On/Off button and dedicated vertical Scroll Up/Down pad".
I take that to mean that it has (like my HP) an area on the right-hand side of the touchpad which, instead of moving the cursor, scrolls the screen.
Is it possible that your finger is sometimes straying into this area of the pad, and causing unexpected screen "jumps"?
The other possibility is that your pad has (again, like mine) a "tap" function, which acts like a mouse click. On mine this is very sensitive. If the arrow cursor was in a different place on the screen from the typing cursor, then an unintended tap could cause the typing cursor to jump.