These only appear in ''Print layout view'' and they indicate the corners of the text boundaries of the page (according to page set up). These help in laying out your text. You can choose whether to show the full text boundaries at Tools >Options. ''View'' Tab.
I've had Microsoft Office 2003 Professional for a while, and recently, whenever I open a word document, there are these L shapes (upside down, righ side up) depending on the each corner, that appear on the screen, but when i got to print, they are not there. I've tried repairing the installation, reinstalling, but those methods don't work. I was wondering if anyone here could help.