We are using fancybox2 for displaying images. Everything works well, but when the larger image is displayed in the fancybox, the page behind scrolls to the top. After closin
Apparently, Fancybox changes the CSS property overflow on body element to hidden when a picture is showed. This causes the background to scroll back to the top. All you have to do is comment out the row saying overflow: hidden !important; in section .fancybox-lock in stylesheet jquery.fancybox.css.
Please see fancybox2 / fancybox causes page to to jump to the top as well.