J. Zaefferer's Accordion Flicker/Jump

Hi, I am trying to implement J. Zaefferer's accordion into my website.
Everything looks great in Firefox, however when viewing it in IE6 & 7,
I am seeing an odd flicker or jump when opening or closing the
accordion. My test is uploaded here: http://teaessare.com/test2/menutest2.html
Does anyone know how to remedy this? Any help would be greatly
appreciated.
Thanks.
Todd