T60 center button standard scroll stop working after undock

[wxxiong]

I love to use the T60 center button for standard scrolling. It is so convenient that I do not need to move my fingers away from keyboard positions.
However, my T60 (running XP) some times loses the standard scrollability after undock.

The procedure I uses is:

• - While it is docking station and running, I press "undock" button to software undock.
  - I press power buttion to put it in standby while still in docking station
  - Then remove it out of docking station to take home.
  - Later when I bring it out of standby, the center button scrolling does not working anymore.

The stange thing is that when this happens, then if I change the "center button" setting to "smooth" scrolling, it does work in smooth mode. (However, I find out that smooth scrolling mode does work in some applications). But regardless on how I re-set it back and forth to standard mode, it does not respond to anything in standard mode when I press the center button. The only solution is to reboot the machine and it start to work again in starndard mode.
My T60 has most of the drviers updated using "System Update". But this problem always exist although not very often. But happens maybe once in 1 ~ 2 weeks.
Not sure if anybody noticed the same issue.