I know EXACTLY why.
INTERNET EXPLORER and other crappy web browsers, however, are NOT moving with the times. With the exception of Internet Explorer 8, which is in beta 2 at the moment, and does make a somewhat decent web-experience.
More explained as to why this is: There are "standards" for constructing and rendering web pages. These rules ENSURE perfect web-page rendering, and no problems.
To compare with non-technical scenarios, when drawing maps you must follow the BOLTS rule — There must be a border, some sense of orientation (an arrow pointing North), a legend, a title, and a reference to the source. If you don't include the legend, then you can have some idea of the map, but your understanding is blurry. Likewise, if there is a legend and you don't know how to read legends, then you are still going to be unable to understand or describe the map.
Solution: Use another web-browser. I recommend Google Chrome. But if you like Internet Explorer, then you MUST download the new beta of version 8.