roller ball weirdness

[Todd And Margo Chester]

Hi All,

I am using Scientific Linux 6.2 x64 and Xfce 4.8.

Since upgrading to 6.2, I have noticed if I scroll too
fast on my mouse wheel, that I change windows.
I wind up in a different program and have to click
back to get back to my original program.

Is this on purpose?  And, is there a way to defeat
the behavior?

Many thanks,
-T