I have installed what I believe is the correct driver from the support site for APS under Windows 7, and in the tasklist I see the Tpshocks.exe process, but I am not sure it is working correctly becausewhile shaking the notebook while watching a movie at 720p, I observed no pause of the video playback.
My thinkpad is T61 (8889 AF2),
Windows7 X86 Ultimate.
To test whether your APS sensor is working properly:
Go to All Programs>ThinkVantage>Active Protection System>Real-time Status, and bump or shake your system gently.
Here is what it looks like with system running and no shocks - you can pick up your system and move it around and see the animated picture move in a synchronization with your movements in all 3 axis - pretty cool!
Now, gently bump your system. You should see the green triangle turn to yellow. If you bump it hard enough or repeatedly, you will see the yellow pause sign appear and your HDD will be parked to avoid damage. It should resume after a second or two automatically, and the indicator should return to the gree arrow.
Click the configuration tab to change the sensitivity levels and actions taken, and even disable APS for a preset amount of time for testing purposes, or disable it completely (not recommended).
Depending on your system, and how the software you are using to watch video works, a video may or may not pause when you shock the system. If you are experiencing audio or video hangs or pauses, try temporarily disabling APS to see if this resolves the symptoms. If so, you may need to adjust sensitivity levels, or reduce the movement of the system while doing audio / video playback that is spooling from the HDD.