Problem: My wife was creating signs for work in Microsoft Word 2007 and each time she added a logo, there would be a mysterious gray line on the left and top of the image. We looked for cropping errors and tried changing the logo. Nothing seemed to work to get rid of the lines until we decided to change the image size.
Solution: The original logo was 406 x 344 and we reduced size to190 x 170. This reduction seemed to fix the problem and there were no more mysterious lines.