Draggable strange behaviour in firefox 3.5.4

Draggable strange behaviour in firefox 3.5.4

Hi,
I am using draggable & droppable on my website to drag menu items to a
calendar grid. It works perfectly in IE8 but in Firefox 3.5.4 I get
these faint red trails across the page when I drag something. These
trails go away when I page down and then up again.
Has anyone else noticed this behaviour. Is there any way to correct
it.
You can see what I mean here.
http://webrecipemanager.com/menuplanner.php
Any help would be much appreciated.
Barb
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