In case someone else has the same issue
Since the last update I did of Wordpress and Atahualpa in 12/2014, on certain posts, with certain order of images and text, the first paragraph of the text following the image was displayed to the top right of the image, with the rest of the text below the image as expected, and the caption area was narrower than the image. I updated Wordpress, but no change. In looking for the issue here, I saw the post http://forum.bytesforall.com/showthr...ight=word+wrap which was titled "Images and Captions produce Text Wrap issue in Internet Explorer only". Although my problem was not just in IE, I tried the fix anyway, and it solved not only the caption width, but also the issue of the first word of the paragraph displaying incorrectly.
I added to my CSS inserts:
which is the width of my center area without the sidebar
I don't know why this affected the wrapping of the paragraph, but it fixed it.