Ajax ModalPopup wrong display in IE8

I have a problem with the modalPopup control when I use it on IE8. The panel which is need to be popUp is already poped up.

As it suppose to look like ( in newer browsers than IE 8), there are panels in a row and when you click on one of them, a windows pops up ( using AJAX modalPopUp)  

And in IE8 it shows the popUp window(panel) without even clicking on one of the panels in the list.

Here is the code :

<asp:updatepanel id="UpdatePanel1" runat="server">

<contenttemplate>

<asp:panelid="PanelManufacturerPictures"runat="server"scrollbars="Auto"width="100%"> 

<asp:datalistid="DataListManufacturersPictures"runat="server"cellpadding="5"repeatdirection="Horizontal"repeatcolumns="11"showfooter="False"showheader="False"cellspacing="16"> 

<itemstyleheight="75px"width="75px"/> 

<itemtemplate>

<asp:imagebutton id="ImageButtonManufacturerPicture" runat="server" alternatetext='<%# eval("manufacturername") %>' Height="100%" ImageUrl='<%# "~/elimansourwcf/manufacturerspictures/"+databinder.eval(container.dataitem, "imageurl") %>' ToolTip='<%# eval("manufacturername") %>' Width="100%" CausesValidation="False" />

<asp:roundedcornersextenderid="RoundedCornersExtenderDetailsManufacturers"runat="server"targetcontrolid="PanelManufacturersDetails"radius="8"bordercolor="Red"></asp:roundedcornersextender> 

<asp:modalpopupextenderid="ModalPopupExtenderManufacturerDetails"runat="server"popupcontrolid="PanelManufacturersDetails"targetcontrolid="ImageButtonManufacturerPicture"backgroundcssclass="modalBackgroundProducts"cancelcontrolid="ButtonManuCancel"></asp:modalpopupextender> 

<asp:panelid="PanelManufacturersDetails"runat="server"backcolor="White"> 

<divdir="rtl"><asp:labelid="LabelManufacturerName"runat="server"font-bold="True"font-size="XX-Large"></asp:label><divstyle="float: right;"><asp:tableid="TableDetails"runat="server"cellpadding="15"font-bold="True"cellspacing="15"><asp:tablerowid="TableRow5"runat="server"><asp:tablecellid="TableCell8"runat="server"width="100px"horizontalalign="Left"columnspan="2"><asp:roundedcornersextenderid="RoundedCornersExtenderDetailsManufacturerCancel"runat="server"targetcontrolid="ButtonManuCancel"radius="8"></asp:roundedcornersextender><asp:buttonid="ButtonManuCancel"runat="server"text="צא מחלון זה"width="75px"causesvalidation="False"backcolor="Red"forecolor="White"font-bold="True"/></asp:tablecell></asp:tablerow></asp:table></div></div>

</asp:panel></itemtemplate></asp:datalist></asp:panel></contenttemplate></asp:updatepanel>

I saw a post

Ajax ModalPopup wrong display in IE8 - IE9 But I didn't understand where to put the css "position: absolute;"

Here is the URL of the site:

www.emansour.co.il

I noticed that this problem occur just when I use the modalPopup in a Bounded Data Control.

Thank you for your help