Scrolling down screen question

[ellen]

I'm sure this is the easiest thing to solve, but I am
stumped! Recently I had to reinstall Windows XP
Professional. Now, when I use the bar on the right side
of the screen to scroll down, there is a "wave" effect,
or a ripple across the screen as we move. I used to just
have a simple moving down line by line sort of
experience, versus all this waviness! Can anyone help me
find where to change this setting?

Thanks!