It sounds like IE is remembering a setting from an old ad
pop-up window. What you need to do is close all your
programs except one IE window. Then, point your mouse at
any part of the grey taskbar that doesn't have a button
beside it. Click the right button and a context menu
opens. Select "Tile Windows" (either horizontally or
vertically should work). IE window should fill the screen.
Close IE to save default window size. Reopen IE and you
should now have all windows at full screen.
If this doesn't work, then you may have spyware on your
system. All the others on this list like Ad-Aware, but
Spybot Search & Destroy works just as well.
