Windows Explorer - Showing Small Screen

Hi all,
I am using windows XP SP2 and i have got a Problem from few days. When i click on a link to bring up it as a new web page it displayed as a small screen and i have to click on the icon at the top right corner to get it full screen.
So Please advice me about this problem and how can i correct this problem.

This website is not affiliated, owned, or endorsed by Microsoft Corporation. It is a member of the Microsoft Partner Program.