I use a track ball also--and have to pop the ball out of the socket and clean lint off of the little lens every so often. I can tell when it needs it because I find my thumb cranking the ball with less result, or the pointer drifts off where I don't want it to go. I haven't had the pages changing like you describe.

My keyboard also has a wheel and it clicks like the trackball wheel, but I never think about using that one. It is possible to accidentally click that wheel and gotten odd results, I suppose, though it hasn't happened to me.

I realized the other day that the functionality of my track ball is not all there--I used to be able to depress the wheel and get a whole menu of stuff. I'll have to revisit the installation disk and see if I actually want any of that back.

SRS