This seems more like a bug then anything else, but maybe I'm overlooking something.
I have this coat that I've rigged that has worked just fine in the past, but now it's doing this weird thing where when I move one of the IKed bone chains, it snaps away from where I move it. Here's a clip, but all I'm doing is pressing G, moving it, then left clicking:
Any ideas as to how this could be happening? Like I said, I've never seen this before, and this same armature has worked just fine in the past.