its probably your IE settings.
go up to the menu, click tools and then internet options. scroll down the list till you get to multimedia, find "enable automatic image resizing" click that on or off. i dont remember which but it will be the opposite of what is selected on your browser. that should fix the problem.
i dont remember if that makes IE resize all images to fit in your browser window or it allows websites to resize images to fit your browser but then let you click to see full images. it will be one or the other and changing it will let you see the full sized image.