The following code produces the error - only in Firefox.  Firebug shows the error - 

The problem goes away if I remove the code that hides the div on the document load - but I need this.  This does work in IE 8.

 

 

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="TestView.ascx.cs" Inherits="Jenzabar.LMS.Portlets.CourseworkPortlet.Views.TestView" %>
<%@ Register Assembly="CuteEditor" Namespace="CuteEditor" TagPrefix="CE" %>
<script type="text/javascript" language="javascript">
    // When first loaded, hide the section
    $(document).ready(function () {
        document.getElementById("divToToggleVisiblity").style.display = "none";  // this is the code that causes the problem
    });

    function toggleInstructionsHeader() {
        if ($("#divToToggleVisiblity").css("display") == "none") {
            $("#divToToggleVisiblity").show("slow");
        }
        else {
            $("#divToToggleVisiblity").hide("slow");
        }
    }
</script>
<div id="divToDoTheToggling" onclick="toggleInstructionsHeader()">
    Toggle Below Div
</div>
<div id="divToToggleVisiblity">
    <CE:Editor ID="editor1" runat="server" Height="200" AutoConfigure="Simple">
    </CE:Editor>
    <CE:Editor ID="editor2" runat="server" Height="200" AutoConfigure="Simple">
    </CE:Editor>
</div>