The PDF preview cannot be displayed at the proper position when page height is very long in IE9 and using Documents and Media Display portlet.
This is because an old rule in css, which may be targeted only to ie7 today.
I could make a simple html which shows the bug. Watch this (scroll to the end of the page) with IE and switch off the css rule for the body, please.
The picture is showed in a very high box without scrollbar
The picture should be showed in bow which is centered to the browser's window. If the box is smaller then the picture, a scrollbar should be appeared.