ASPToolKit: Accordion Control rendering error message in Design Mode

I'm receiving the following error in DesignMode with the Accordion1 control. Not sure what is causing this. This is my ASP WebApp.

Error Rendering Control - Accordion1
An unhandled exception has occurred. Collection was modified; enumeration operation may not execute.

VS 2005 Pro
ASP Ajax
XP SP3

Thanks.

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true"
    CodeFile="SmartBlnd.aspx.cs" Inherits="SmartBlnd" Title="Smart Blinding Definition" %>

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp1" %>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="Server">
    <asp:Label ID="Label2" runat="server" Text="Project#" Width="69px"></asp:Label>
    <asp:TextBox ID="TxtBoxProject" runat="server" MaxLength="6" ToolTip="Enter Covance Project Number"
        Wrap="False"></asp:TextBox>
    <asp:Button ID="Button2" runat="server" OnClick="Button1_Click" Text="Search" />
    <asp:Button ID="btn_SendEmail" runat="server" Text="Email" Visible="False" OnClick="btn_SendEmail_Click" />
    <asp:Label ID="lbl_CTSmartHeader" runat="server" Text="No Records found  in CT" Visible="False"
        Width="135px"></asp:Label>
    <asp:Label ID="lbl_SmartHeader" runat="server" Text="No records found in Smart" Visible="False"
        Width="69px"></asp:Label>&nbsp;
    <asp:TextBox ID="txt_EmailResults" runat="server" Visible="False"></asp:TextBox>
    <asp1:ToolkitScriptManager ID="ToolkitScriptManager2" runat="server">
    </asp1:ToolkitScriptManager>
    &nbsp;
    <asp1:Accordion ID="Accordion1" runat="server">
        <Panes>
            <asp1:AccordionPane ID="AccordionPane1" runat="server">
                <Header>
                    <a href="" onclick="return false;" class="accordionLink">CT Specimen Classes </a>
                </Header>
                <Content>
                    <asp:GridView ID="GridView1" runat="server" BackColor="White" BorderColor="#CCCCCC"
                        BorderStyle="None" BorderWidth="1px" CellPadding="3">
                        <FooterStyle BackColor="White" ForeColor="#000066" />
                        <RowStyle ForeColor="#000066" />
                        <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
                        <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
                        <HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
                    </asp:GridView>
                </Content>
            </asp1:AccordionPane>
            <asp1:AccordionPane ID="AccordionPane2" runat="server">
                <Header>
                    <a href="" onclick="return false;" class="accordionLink">lbl_SmartHeader</a>
                </Header>
                <Content>
                    <asp:GridView ID="GridView2" runat="server" BackColor="White" BorderColor="#CCCCCC"
                        BorderStyle="None" BorderWidth="1px" CellPadding="3">
                        <FooterStyle BackColor="White" ForeColor="#000066" />
                        <RowStyle ForeColor="#000066" />
                        <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
                        <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
                        <HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
                    </asp:GridView>
                </Content>
            </asp1:AccordionPane>
        </Panes>
    </asp1:Accordion>
</asp:Content>

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Accordion-Error.jpg