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My unerstanding of this is that the VR is designed to counter micro-movements that occur when you hand-hold (like your heartbeat pulsing blood through your arteries, which can have an effect), but when on a solid stable support the VR can end up trying to correct for motion of the subject (since that's the only movement that the camera will sense). I believe the newer version of VR will allow for tripod use, though.
My 18-200 VR has two switches - on and off, and Normal/Active. In Normal mode, you can pan with a runner or racing car, and it only restricts vertical motion. Active restrains movement in both the vertical and horizontal axes, so it is best for still shots.
In either mode when shooting off a tripod with VR on, it will hunt. At low shutter speeds, this can introduce blur and at any shutter speed, you may get a different framing than what you expect. The latter will create problems if you are planning on layering the exposures for HDR, or when shooting sequences for time encapsulation. Each layer may need to be manually aligned.
Well I had a laugh once with my video camera, which has an anti shake function. I had it on as I was zooming in to capture some runners in a marathon. Suddenly the anti shake system got it wrong as I zoomed in on one guy jogging straight towards me and it started keeping him still in the middle of the frame as he was jogging and the background behind him was jumping up and down. Quite a laugh really!!!!