Mottled Houdan hen crazy as a loon!

[Tropit]

I have a mixed batch of chicks that I received in March. They're 4 months old now. One of them is a Mottled Houdan. She's absolutely beautiful, but I think that she has a screw loose. She cowers in a dark corner of the coop most of the time and then bolts out into the sunlight, flapping and screeching, then goes back to her corner. All of the other birds get out of her way whenever possible. I wondered if she may have a problem with her eyesight, but after watching her for awhile, I think that she can see fine. Does anyone else have a similar problem with this breed? Any suggestions about any other issues which may cause her curious behavior? Thanks.
~ Cindy