I am sorry if this post is a duplicate to a reply I posted earlier, but it appeared that that thread may not have been active.

I am using UI 1.8.6 and  jQ 1.4.4 and the latest IE9 beta (v7.930)

I encounter the standard "IE-is-breaking" error when trying to open an accordion element other then the first one.

To wit, the error is: 

'null' is null or not an object  jquery-ui-1.8.4.custom.min.js, line 287

Does accordion remain a problem for others in IE9?

Specifically, on selecting the first accordion element, all is well - but on selecting any other, IE9 throws an error as described above.

I can supply additional code but it really is a standard implementation I have used before.

//INIT THE OPTIONS

 var accordionOptions = {

  header: "h5",

  active: 0,

  fillSpace: false,

  collapsible: true,

  autoHeight: false,

  disabled: false,

  animated: "slide"

 }

//BIND TO ELEMENT

$("#accordionElement").accordion(accordionOptions);

Note that I use the following to do a bunch of stuff on select:

$("#accordionElement").bind("accordionchangestart", function(event, ui) {

//do stuff based on a switch variable as follows:

  var currentAccordionSection = $("#accordionElement").accordion("option", "active");

  switch(currentAccordionSection) {

   case 0:

//and so on . . .

  }

});

Note that UI 1.8.6 and  jQ 1.4.4 both work like champs in latest Mac / Win for Safari / FF / Chrome.  Opera remains a problem for another day.

BTW - dialog and position seem to have no problems for me in IE9 - just accordion as above.