I didn't say you "must" reboot. I said youcould try rebooting. Every once in a while I wake my system from sleep mode and there's no controlling the mouse pointer. It goes all over the place. By restarting, the problem goes away. That's why I mentioned it. It seems you tried what I suggested.
Johnny gave you some good advice. To be more specific, I suggest that you start here- HP Support & Drivers | United States
and try to download/install the latest driver for your touchpad.
I'm assuming you're in the United States.