Fix the Cross Functional Button on Toshiba Portege M200

I recently bought a second-hand Toshiba M200 tablet PC. It's great!

I just had one problem, the little 4-way button, which looks like a mini joystick and is technically known as the "Cross Functional Button", basically didn't work. It was more of a non-functional button, really.

It is supposed to allow you to scroll in all 4 directions, which is a very important thing when in tablet mode, because you don't have access to the keyboard. But, it just output numbers instead of scrolling.

I searched and searched and found nothing particularly helpful. Eventually I went to the Toshiba site, found the "Toshiba Tablet PC Buttons Driver", installed it, and my problem was solved!
I have no idea why, out of all the pages I searched, no-one mentioned this.  I found one where someone had the exact same problem, but resorted to a much more complicated solution.  So, this post is here for the next person who has the same problem.  Hopefully, you'll find this post and save yourself the hours of frustration that I had.  Just install the driver ;-)
PS while you're there, install the accelerometer driver too, if you have this problem.