This issue might be related to  http://forum.jquery.com/topic/sortable-offset-when-element-is-dragged-and-page-scrolled-down-ff

I have a sortable list on a page, user needs to scroll at the bottom of the page down to see the list. There are some relative positioned divs in the DOM hierarchy (which I believe is the cause of the problem). When an item is moved, it gets positioned absolutely - jQuery UI 1.8.10 line 3289 (the line above is a comment: TODO: Still need to figure out a way to make relative sorting possible). The parent element shrinks down and when the placeholder is inserted, it does not scroll back, so the page moves. 

One workaround I thought about is setting the height of the container, but the start callback is called after the element shrinks. The list is dynamic, so the height cannont be set once and for all.

Any help is appreciated, thanks!