I am using Version 10.3.20103.2134.

I have a WebDataMenu on a user control that is used by every page in our app to provide a uniform menu.

On pages that include any of these three AJAX controls (Accordion, Tabs or ModalPopupExtender)

as soon as the page is posted back the following error occurs:

SCRIPT5007: Unable to get value of the property 'nodeName': object is null or undefined

In the code below, the debugger shows the activeElem item within the if statement as null. This happens ONLY in IE 9, Firefox shows this as an "input" item and works fine.

_onDocumentMouseOverHandler: function(e)
    {
        this.__x = e.clientX;
        this.__y = e.clientY;
       
        var activeElem = document.activeElement;
        if(!this.__controlActive && activeElem.nodeName != "BODY" && activeElem.nodeName != "HTML")
        {
            this.__lastFocusedElement = activeElem;

            if (this.__lastFocusedElement && this.__lastFocusedElement.nodeName == "INPUT")
            {
                this.__lastFocusedInputCaretPosition = this.__lastFocusedElement.value.length;
            }
        }
    }

It appears other AJAX controls (such as CascadingDropDowns) don't cause a fuss.

Does anyone have any ideas?