When you click on the maximize button, IE opens to a screen larger than your physical screen? Do other programs do this as well?
If yes, then you need to adjust the vertical/horizontal settings of your monitor. It may be the monitor that is not retaining its settings. Then check Control Panel --> Display --> and check your resolution settings. Then click on Advanced and make sure the proper video card is identified and that the settings are correct.
If other programs are not doing this screen "beyond reach", then it is something in IE that is doing this. Go to Tools --> Internet Options and on the General tab... compare each of the Fonts and Accebility options to what you need. Also check the View --> Text --> Size option (which is it's own submenu in IE 5.5) and make sure that that's set properly.