OS: Ubuntu 13.10
Linux kernel: 3.11.0-18-generic
Short description of error
In this .blend file, keyframing off the Animated property of a rigid body (found in Properties window -> Physics context -> Rigid Body panel), is causing object to reset to original position and not undergo any physics simulation.
Exact steps for others to reproduce the error
I was unable to reproduce the error from scratch. But if you open the .blend file below and scrub through the first 10 frames you will see that at frame 6, when Animated is disabled, it returns to original position.