Bone rotating entire mesh in Blender, but not in Unity

I have a very bizarre problem. I had a working mesh/rig combination. Then I tried making some animations, and now one of the bones rotates the entire mesh, instead of just the part it's supposed to. However, this problem only happens in Blender; when I rotate the armature in Unity, it works perfectly. All of the bones are weight-painted correctly, so I don't think that's the problem. I'm at my wit's end trying to fix this. Here's a video demonstrating my problem.

https://www.youtube.com/watch?v=3YlrEH3ZY8M

And here's my .blend file, in case it sheds any light on the problem.

http://www.mediafire.com/download/yj49i43lih4bl3e/spyro.blend