One of many RadDatePicker controls on my page:  

i have two combobox with checkbox inside. this is my code about combobox

<telerik:RadComboBox ID="rcbProduct" runat="server" AllowCustomText="True" AppendDataBoundItems="True" 

DropDownWidth="700px" EmptyMessage="Choose Product" Filter="Contains" ForeColor="Blue"

HighlightTemplatedItems="True" MarkFirstMatch="True" MaxHeight="150px" OnItemDataBound="rcbProduct_ItemDataBound">

<HeaderTemplate>

<ul>

<li class="col1" style="width: 120px">ProductName</li>

<li class="col2" style="width: 120px">ModelNumber</li>  

<li class="col3" style="width: 70px">Vender</li>

<li class="col4" style="width: 60px">Price</li>  

<li class="col5" style="width: 150px">Image</li>

</ul>  

</HeaderTemplate>

<ItemTemplate>

<asp:Panel ID="divUser" runat="server">

<ul>

<li class="col1" style="width: 120px">

<%

# DataBinder.Eval(Container.DataItem, "f_ProductName").ToString().Trim()%>

</li>

<li class="col2" style="width: 120px">

<%

# DataBinder.Eval(Container.DataItem, "f_ModelNum").ToString().Trim()%>

</li>

<li class="col3" style="width: 70px">

<%

#DataBinder.Eval(Container.DataItem,("f_VenderName")) %>

</li>

 <li class="col4" style="width: 60px">

<%

# DataBinder.Eval(Container.DataItem, "f_Price").ToString().Trim()%>

<li class="col5" style="width: 150px">

<asp:Image ID="img" runat="server" Height="80px" ImageAlign="AbsMiddle" Width="80px" />

<asp:Label ID="lblImg" runat="server" Text='<%# Eval("f_ImageProduct") %>' Visible="false"></asp:Label>

</li>

</ul>

</asp:Panel>

</ItemTemplate>

</telerik:RadComboBox>


and this is javascript code:

<script type="text/javascript"> 

var cancelDropDownClosing = false;

function StopPropagation(e)

{

//cancel bubbling

    e.cancelBubble = true;

    if (e.stopPropagation)

    {

        e.stopPropagation();

    }

}

function onDropDownClosing()

{

cancelDropDownClosing =

false;

}

function onCheckBoxClickPro_Shop(chk)

{

var combo1 = $find("<%= rcbProduct_Shop.ClientID %>");

//prevent second combo from closing

"");

cancelDropDownClosing =

true;

//holds the text of all checked items

var text = "";

//holds the values of all checked items

var values = "";

//get the collection of all items

var items = combo1.get_items();

//enumerate all items

for (var i = 0; i < items.get_count(); i++)

{

var item = items.getItem(i);

//get the checkbox element of the current item

var chk1 = $get(combo1.get_id() + "_i" + i + "_chk1");

if (chk1.checked)

 {

text += item.get_text() +

"," ;

values += item.get_value() +

",";

}

}

//remove the last comma from the string

text = removeLastComma(text);

values = removeLastComma(values);

if (text.length > 0)

{

//set the text of the combobox

//combo.set_text("");

combo1.set_text(text);

//update the treeview in the second combobox

}

else

{

//all checkboxes are unchecked

//so reset the controls

combo1.set_text(

"");

}

}

function onCheckBoxClickPro(chk)

{

var combo = $find("<%= rcbProduct.ClientID %>");

//prevent second combo from closing

combo.set_text(

"");

cancelDropDownClosing =

true;

//holds the text of all checked items

var text = "";

//holds the values of all checked items

var values = "";

//get the collection of all items

var items = combo.get_items();

//enumerate all items

for (var i = 0; i < items.get_count(); i++)

{

var item = items.getItem(i);

//get the checkbox element of the current item

var chk1 = $get(combo.get_id() + "_i" + i + "_chk1");

if (chk1.checked)

{

text += item.get_text() +

"," ;

values += item.get_value() +

",";

}

}

//remove the last comma from the string

text = removeLastComma(text);

values = removeLastComma(values);

if (text.length > 0)

{

//set the text of the combobox

//combo.set_text("");

combo.set_text(text);

//update the treeview in the second combobox

}

else

{

//all checkboxes are unchecked

//so reset the controls

combo.set_text(

"");

}

}

</script>


i use same script for two combobox . In FireFox is ok no problem but when i open it with IE.7 or IE 8 . They show a message:
"A script on this page is causing your web browser to run slowly. If it continues to run, your
computer might become unresponsive"

I test the problem and if i delete one javascript and dont load data for a combobox it's ok if i load data for two combobox sametime . This Problem will happen and show alert above. Please help me to solve this Problem .Thanks alot