Grey stars won't go away

I have always preferred to keep my songs organized by start rating. That way, all I have to do is give a song, say, five stars and it appears in my "top rated" playlist and at the top of my song library.

Until recently.

I want to remove "The Eyes of Sharbat Gula" from the top. It will not go away. I right-click, scroll to the star rating, select "none," and nothing happens. I downgraded it to four stars and it moved. When I tried again to remove all the stars, it went right back on top.

How can I put this little bugger back in its place?