So, like a few others, I found that turning off the 3/4 finger tapping stops the problem, but only until you restart the PC.

A few people mentioned that they also have Synaptics pointer so I...

THIS SOLVED MY PROBLEM!

Very much appreciated! It was so annoying as I use the trackpad to scroll up and down all the time; I'd looked in the mouse/trackpad area but hadn't seen this settings...