Hide modalpopupextender inside usercontrol

Hi All,

I have modalpopupextender in updatepanel which is in usercontrol.

<asp:ModalPopupExtender ID="mpeConfirmNames" runat="server" TargetControlID="hlPopName" 
    PopupControlID="pnlConfirmNames" BackgroundCssClass="modalBackground" CancelControlID="btnConfirmNamesCancel" /> 
<asp:Panel ID="pnlConfirmNames" runat="server" Style="text-align: left; width: 450px; 
    background-color: #EFF3FB; border-width: 2px; border-color: gray; border-style: solid; 
    padding: 10px;"> 
    Please confirm that First and Last names are spelt as they appear on your Passport 
    as name correction fees may apply or you may be denied boarding. 
    <br /> 
    <br /> 
    <asp:Label ID="lblTest" runat="server" /> 
    <div align="center" id="grdUser"> 
        <asp:GridView ID="UserGridView" runat="server" AutoGenerateColumns="False" Width="90%"> 
            <HeaderStyle BackColor="#BFE2F9" Font-Bold="true" Font-Size="12px" ForeColor="#000000" /> 
            <Columns> 
                <asp:BoundField HeaderText="First Name" DataField="Firstname" /> 
                <asp:BoundField HeaderText="Middle Name" DataField="Midname" /> 
                <asp:BoundField HeaderText="Last Name" DataField="Lastname" /> 
                <asp:TemplateField HeaderText="DOB"> 
                    <ItemTemplate> 
                        <%# Eval("Day") + "/" + Eval("Month") + "/" + Eval("Year")%> 
                    </ItemTemplate> 
                </asp:TemplateField> 
            </Columns> 
        </asp:GridView> 
    </div> 
    <asp:Label ID="lblUserName" runat="server" /> 
    <div style="text-align: center;"> 
        <asp:Button ID="btnConfirmNamesCancel" runat="server" Text="Change" TabIndex="0" 
            OnClick="btnConfirmNamesCancel_Click" /> 
        &nbsp;&nbsp; 
        <asp:Button ID="btnConfirmNamesOK" runat="server" Text="Confirm" TabISndex="1" OnClick="btnConfirmNamesOK_Click" /> 
    </div> 
</asp:Panel> 
<asp:Button ID="hlPopName" runat="server" Visible="false" />

LoadSummary() takes few seconds to process so I want to disable button(btnConfirmNamesOK) Or hide the modalpopupextender.

I have tried codebehind

 protected void btnConfirmNamesOK_Click(object sender, EventArgs e)
        {            
            mpeConfirmNames.Hide();
            LoadSummary();
        }        

also tried

Javascript to disable button but didn't work!

    function disableButton() {
        var arrInputs = document.getElementById('<%= btnConfirmNamesOK.ClientID%>');
        arrInputs.disabled = true
    } 

 <asp:Button ID="btnConfirmNamesOK" runat="server" Text="Confirm" TabISndex="1" OnClick="btnConfirmNamesOK_Click" OnClientClick="window.setTimeout('disableButton()',0); return true" Text="OK"/>

Best Regards,

Damodar