Icons rearrange themselves

I will arrange the icons in fences the way I want them so I can find them without hunting, but it seems I need to rearrange them daily because they randomly rearrange themselves within the fence.  I know I can take a picture of the desktop and then replace the messed up desktop with the correct layout, but I shouldn't have to do this every day.  Also, this usually happens on only two windows.  Is there something I can do to keep my icons from randomly moving within their fence?