total_carnage, Follow the instructions at the link below.
How do I have an Internet Explorer 7 (IE 7) window open in the maximized position every time?
You could also press your F11 key on the keyboard and see if that's what you mean.
I have seen a thread explaining asking how to fix this problem before, but I did not fully understand the answer, so here goes.
I have recently downloaded and uninstalled (don't ask me why) both windows XP SP3 and IE8. After uninstalling both, I now have SP2 and IE7. I have not encountered this problem before, but when I click the fullscreen button, it goes fullscreen, but the banner at the top will not disappear. This did not happen to me once before the downloads & uninstallations. Could somebody please provide an answer?