VR in the Nikkor Lenses. For that matter any vibration dampening system.
It looks for and tries to dampen any motion that the camera may be subjected to. If the camera is stationary like on a tripod, it will still attempt to move the VR system to detect motion.
So you turn off your VR/IS/ dampening system.
When panning, you might want to have it stabilize the vertical motion, but if you have it on for horizantal, it is likely to get confused and will reduce the sharpness.
As was mentioned, Some systems allow you to turn the horizontal VR/IS/Dampening off.
If your shutter speed is fast enough, it's likely VR/IS/Dampening will only give you the benefit of running your battery dead faster.
So those are three of the times you don't need/want VR/IS/Dampening.