Weird spikes when I move an armature

So I just began using Blender 2.5, and I have had no trouble what so ever with using it. However, every time I move this one arm, an ugly spike comes out of my mesh’s side. I fixed this on other parts of my mesh’s body by subtracting/adding weight in Weight Paint, but this spike proves difficult and I want to know how to get rid of it. I attached a few pictures so you might understand what I’m talking about (I outlined the problem in a red circle)
Thanks. :wink:

Obviously, that vertex i weighted to the the wrong bone. In weight painting mode, select bones of the arm on by one until the vertex lights up. Then weight paint to 0 for that bone.

Thank you so much!! It turned out to be a finger bone that was messing it up! Again, thanks.