Weight Paint topology distortion

When I move the leg, a topology distortion occurs on the shin. I went through all the body parts to see if part of the shin was mistakenly selected, but didn’t see anything wrong. How can I find out what is causing this problem and how do I fix it?

screen shot of what I’m talking about:

blend file:
http://www.pasteall.org/blend/24007

Note that when you select shin appears correct because the bolt is checked also.
However if you set the thigh also the same bolt is checked.
Enter the edit mode in the thigh group - select the part being distorted (bolt) and hit remove.

I never noticed that. Thanks. I think that’s fixed now. I still have a few more issues. I will have to post yet more requests for help. Speaking of which…I noticed I included the wrong screenshot above. I thought I figured out what the dotted red line along the z axis was. It only appeared when I selected the middle f_middle.01.R. I had done some retopology on the f_middle.01.L. So I reparented the mesh to the armature. And the dotted red line went away. But now it appears only when I select the right thigh. (I didn’t do any retopology there. And I reparented the mesh to the armature once again, just in case. But it had no effect.) Any ideas what that is?