Judging from the large number of comments rotating a picture in Photo Viewer seems to be a common problem and I don't understand why. Have spent a lot of time wading through these postings and still am no closer to an answer. I followed the directions in http://windows.microsoft.com/en-US/windows7/Rotate-a-picture-using-Windows-Photo-Viewer and everything works fine until reaching step 3, where the picture is in Photo Viewer ready to be rotated except that neither rotation arrow functions. Would appreciate someone offering a cogent explanation for the simple function of turning a picture on the screen from sideways to vertical. Many thanks.