Let me guess, you where on an object and then deleted it after some time?
If I'm right, it means that it's not really a bug but and optimization (or to be precise, a unhandled condition in an optimization).
LFS (or any physics engine), put a rigidbody into "sleep" when it is no longer moving (and after a while), to save performance. But when you remove a object, LFS doesn't "wake up" objects that are near it.