Unwanted blank line in text box

I use IND CS3 to create a 36 page newsletter for my computer group. In the past few months I’ve encountered a problem on two separate pages of the Journal. On the right hand column of page 7, and page 22, I have a blank line in the text. It may occur in the middle of a sentence or after a paragraph return. I cannot backspace to fill that line. The blank line is always in the same location vertically in the column. It is higher on page 22 than page 7, but behaves the same way.

The interesting thing is that if I drag that entire text box out of that part of the page, the blank line disappears and the text or space becomes normal. Move the text box back into the page and the blank line re-appears. Put new text into the column and the blank space appears in it.

I had thought that there must be some sort of hidden item filling that line, text, graphic, or whatever. However, I have been unable to find what that might be. I have looked at layers, and possible other frames or boxes in that column. I have checked the master pages and there doesn’t seem to be anything different on these pages.