modal popup appears on every tick of timer in asp

Here is my code :
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<div style="position:absolute; top: 266px; left: 293px;">
<asp:panel class="popupConfirmation" id="DivConfirmation5"
runat="server">
<div class="popup_Container">
<div class="popup_Titlebar" id="Div14">
<div class="TitlebarLeft">
Message</div>
<div class="TitlebarRight" önclick="$get('ButtonDeleteCancel').click();">
</div>
</div>
<div class="popup_Body">
<p>
<asp:Label ID ="lblrecharge" runat="server">      <%--<asp:HyperLink ID="hyplogin" runat="server" NavigateUrl="~/RechargeOption.aspx">RECHARGE NOW</p>--%>
</div>
<div class="popup_Buttons">
<%-- <asp:Button ID="RechargeNow" runat="server" OnClick="RechrgeNowC()" Text="Recharge Now" />--%>
<input id="RechargeNow" type="button" value="Recharge Now" style="display:none;" />
<asp:Button ID="re" runat="server" PostBackUrl="~/RechargeOption.aspx" Text="Recharge Now" Height="30" />    
<input
id="NotNow" type="button" value="Not Now" önclick="return NotNow_onclick()" style="height:30px;" /></div>
</div>

<%-- --%>
<asp:ScriptManager ID="sc" runat="server">
<cc1:ModalPopupExtender ID="mpe5" runat="server"
TargetControlID="Button3"
PopupControlID="DivConfirmation5"
BackgroundCssClass="ModalPopupBG"
DropShadow="true"
OkControlID="RechargeNow"

CancelControlID="NotNow"
PopupDragHandleControlID="Panel3" >
<input
id="Button3" runat="server" type="button" style="display:none;" />

<asp:Button ID="Button2" runat="server" Text="Button" Visible="false" />
</div>


<asp:Timer ID="tm" runat="server" Enabled="true" Interval="1000" OnDisposed="Timer_Disposed" OnTick="Timer_Tick" >

<asp:UpdatePanel ID="up" runat="server">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="tm" EventName="Tick" /></Triggers>
<contenttemplate>
<div style="position:absolute; top: 240px; left: 470px; height: 50px; width: 320px;">


<asp:Label ID="lbtime" runat="server" Font-Bold="true" ForeColor="Black" >
<br />
<asp:Label ID="lbtime0" runat="server" Font-Bold="true" ForeColor="Black" >


</div>




<div style="position:absolute; top: 310px; left: 440px; width:420px; height: 400px; "
id="pic1" visible="true"
runat="server"></div>





when i click not now button the modal popup reappears .here you can see i am running a lebelled asp timer

code behind is as follows


protected void Page_Load(object sender, EventArgs e)
{
try
{

lblrecharge.Text = "HELLO " + Request.Cookies["USERNAME"].Value + " YOU HAVE " + Request.Cookies["pointsreq"].Value + " LESS POINTS IN YOUR ACCOUNT TO PROCEED RECHARGE YOUR ACCOUNT ";

try
{
mpe5.Show();
}
catch (Exception)
{ }

// Response.Write("<script>alert('HELLO " + Request.Cookies["USERNAME"].Value + " YOU HAVE " + Request.Cookies["pointsreq"].Value + " LESS POINTS IN YOUR ACCOUNT TO PROCEED RECHARGE YOUR ACCOUNT');</script>");
pic1.Visible = true;
tm.Enabled = true;
}