I have downloaded the newest video driver from Dell and installed. I have done a truly clean reboot in win 8 with all startup items turned off. Nothing keeps the duplicate line from appearing periodically. When it appears it is after completing a paragraph and kitting Enter to start the new paragraph. It only happens every day or say, but always after hitting Enter at the end of a paragraph. Then the last line is duplicated in the display without me entering any test. If I delete the previous line then remaining last line is shown as a duplicate. the only to stop the display behavior is to save, quit and restart. then it si fine until it happens again. It only occurs in MS Word 2013.