I.E. 5.5 maximizes at wrong coords

Internet Explorer locates at a position about 80 pixels from both the top and left edges of the Windows desktop whenever I click the browser’s Maximize button. As it is maximized, I can’t manually drag it to where it should be to fill the desktop.This began after I visited a website several days ago & my browser window was unexpectedly shrunk to about 1/3 its original size!(I was using current anti-virus and firewall). How is this corrected and what caused it?