Windows 7 - Jitter in mouse wheel scrolling

I use the mouse wheel for scrolling and have an annoying problem with jitter when scrolling up. Sometimes the image on the screen jitters up and down with each detent in the wheel instead of scrolling in the same direction. I have not noticed this when scrolling down, only when scrolling up. The mouse is an MS Wireless 3500 with the latest drivers and mouseware from Microsoft and plugged into an HP G72 laptop.

Any thoughts?

If it is just the wheel that is making things jump I would think you have garbage inside and arround the wheel sensor. Over time junk gets down there. If you can you may have to dissassemble the mouse and look at the wheel sensor.
Video

I've observed "feature" since the mouse was new and it's barely six months old now. The problem only affects scrolling up and it isn't a jerk, it's a jitter that causes the scrollable content to jitter up and down even though the wheel is scrolling up.

Have you plugged in another USB wired mouse to see if it still happens?
I would uninstall the mouse divers and reboot to see if Windows 7 will add new drivers.