Collection was modified; enumeration operation may not execute.

[InvalidOperationException: Collection was modified; enumeration operation may not execute.]
   System.Web.UI.ControlCollectionEnumerator.MoveNext() +12538578
   Telerik.Web.UI.RadFormDecorator.FindAndDecorateControls(Control parent) +779
   Telerik.Web.UI.RadFormDecorator.FindAndDecorateControls(Control parent) +755
   Telerik.Web.UI.RadFormDecorator.FindAndDecorateControls(Control parent) +755
   Telerik.Web.UI.RadFormDecorator.FindAndDecorateControls(Control parent) +755
   Telerik.Web.UI.RadFormDecorator.FindAndDecorateControls(Control parent) +755
   Telerik.Web.UI.RadFormDecorator.FindAndDecorateControls(Control parent) +755
   Telerik.Web.UI.RadFormDecorator.FindAndDecorateControls(Control parent) +755
   Telerik.Web.UI.RadFormDecorator.ControlPreRender() +761
   System.Web.UI.Control.PreRenderRecursiveInternal() +113
   System.Web.UI.Control.PreRenderRecursiveInternal() +222
   System.Web.UI.Control.PreRenderRecursiveInternal() +222
   System.Web.UI.Control.PreRenderRecursiveInternal() +222
   System.Web.UI.Control.PreRenderRecursiveInternal() +222
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4297

• Can the details of the process using these temp files be explained in hopes of helping where to check next?
• How are these files automatically deleted, what is the trigger?
• Are there known reasons that the files would not be deleted?
• Are there logs to capture the delete errors?  No errors are being raised by the application, we found out when we ran out of space.

<%@ Page Title="" Language="vb" AutoEventWireup="false" MasterPageFile="~/Site.Master"
    CodeBehind="SplitterDemo.aspx.vb" Inherits="RadControlsWebApp.SplitterDemo" %>
 
<asp:Content ID="Content1" ContentPlaceHolderID="cnthead" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ScriptPlaceHolder" runat="server">
    <telerik:RadScriptBlock ID="scr" runat="server">
        <script type="text/javascript">
            OnRequestEnd = function (sender, arg) {
                CheckSplitterSize();
            }
        </script>
    </telerik:RadScriptBlock>
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="cphTopPage" runat="server">
</asp:Content>
<asp:Content ID="Content4" ContentPlaceHolderID="cphRadButtons" runat="server">
    <div>
        <telerik:RadAjaxPanel ID="rapContent" runat="server" LoadingPanelID="appLoadingPanel">
            <asp:Button ID="btnClickMe" runat="server" Text="Click Me" />
        </telerik:RadAjaxPanel>
    </div>
</asp:Content>
<asp:Content ID="Content5" ContentPlaceHolderID="cphContent" runat="server">
    <telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server" LoadingPanelID="appLoadingPanel"
        ClientEvents-OnResponseEnd="OnRequestEnd">
        <asp:CheckBox ID="chkSelect" runat="server" Text="Show/Hide Panel" AutoPostBack="true" />
        <asp:Panel ID="pnlHiddenPanel" runat="server" Visible="false">
            <div style="height: 800px">
                This is very long text.
                <br />
                <asp:Label ID="lblSelect" runat="server" />
                <br />
                <asp:DropDownList ID="drpSelect" runat="server" AutoPostBack="true">
                    <asp:ListItem Text="C#" Value="C#" />
                    <asp:ListItem Text="Asp.Net" Value="Asp.Net" />
                    <asp:ListItem Text="SQL" Value="SQL" />
                    <asp:ListItem Text="Telerik" Value="Telerik" />
                </asp:DropDownList>
            </div>
        </asp:Panel>
        <br />
        Name:
        <asp:TextBox ID="txtName" runat="server"></asp:TextBox>
        <asp:RequiredFieldValidator ID="req1" runat="server" ControlToValidate="txtName"
            ErrorMessage="Name required" Text="!" ForeColor="Red"></asp:RequiredFieldValidator>
        <br />
        Last Name:
        <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox>
        <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtLastName"
            ErrorMessage="Last Name required" Text="!" ForeColor="Red"></asp:RequiredFieldValidator>
        <br />
        Age:
        <asp:TextBox ID="txtAge" runat="server"></asp:TextBox>
        <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="txtAge"
            ErrorMessage="Age required" Text="!" ForeColor="Red"></asp:RequiredFieldValidator>
    </telerik:RadAjaxPanel>
</asp:Content>
Content Page Code Behind:

Public Class SplitterDemo
    Inherits System.Web.UI.Page
 
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
 
    End Sub
 
    Private Sub btnClickMe_Click(sender As Object, e As System.EventArgs) Handles btnClickMe.Click
 
    End Sub
 
    Private Sub chkSElect_CheckedChanged(sender As Object, e As System.EventArgs) Handles chkSelect.CheckedChanged
        ConsumeTime(2)
        pnlHiddenPanel.Visible = CBool(chkSelect.Checked)
    End Sub
 
    Private Sub ConsumeTime(ByVal seconds As Integer)
        Dim ticker As DateTime = DateTime.Now()
 
        While DateDiff(DateInterval.Second, ticker, DateTime.Now) <= seconds
 
        End While
    End Sub
 
    Private Sub drpSelect_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles drpSelect.SelectedIndexChanged
        lblSelect.Text = "You selected :" + drpSelect.SelectedValue
    End Sub
End Class
Common.js :

$.getRadWindow = function (win) {
    var oWindow = null;
    if (win.radWindow) oWindow = win.radWindow;
    else if (win.frameElement && win.frameElement.radWindow) oWindow = win.frameElement.radWindow;
    return oWindow;
}
 
 
$.showRadWindow = function (id) {
    var window = $find(id);
    if (window != null) {
        window.set_status("Ready");
        window.show();
        return true;
    }
    else
        return false;
}
 
 
$.showInCenter = function (ctrl) {
    posY = $.getScrollOffset() + ($.getInnerHeight() / 2) - (ctrl.height / 2);
    posX = document.documentElement.clientWidth / 2 - (ctrl.width / 2);
    $(ctrl).css({ position: "relative", top: posY + "px", left: posX + "px" });
}
 
$.getInnerHeight = function () {
    var y;
    if (self.innerHeight) // all except Explorer
        y = self.innerHeight;
    else if (document.documentElement && document.documentElement.clientHeight)
        y = document.documentElement.clientHeight;
    else if (document.body) // other Explorers
        y = document.body.clientHeight;
    return (y);
}
 
$.getScrollOffset = function () {
    var y;
    if (self.pageYOffset)
        y = self.pageYOffset;
    else if (document.documentElement && document.documentElement.scrollTop)
        y = document.documentElement.scrollTop;
    else if (document.body)
        y = document.body.scrollTop;
    return (y);
}
application.css :

body
{
    background-color: #C0C0C0;
    margin: 0;
    padding: 2px;
    font-family: Verdana, Arial, Helvetica, sans-serif;
    font-style: normal;
    line-height: 18px;
    color: #333333;
    font-weight: normal;
    font-size: 12px;
    height: auto;
}
 
a
{
    text-decoration: underline;
}
 
a:hover
{
    color: #d0981b;
}
 
.ValidationSummary
{
    border: 2px solid red;
    color: red;
    margin: 5px 0px;
    padding: 15px;
    background: #fff url(images/errors.png) no-repeat 5px 50%;
}
 
.ValidationSummary ul
{
    margin: 0;
    padding: 0;
    margin-left: 60px;
    list-style-type: square;
}
 
.InformationMessage
{
    border: 2px solid yellow;
    color: maroon;
    margin: 5px 0px;
    padding: 15px;
    background: #fff url(images/information.png) no-repeat 5px 50%;
}
 
.InformationMessage li
{
    margin: 0;
    padding: 0;
    margin-left: 60px;
    list-style-type: square;
}
 
.ScrollingDiv
{
    position: relative;
    border-color: #4682b4;
    border-style: solid;
    background-color: #FFFFCC;
}
 
.ScrollingMenu
{
    position: relative;
}
 
.LoadingPanel
{
    z-index: 100000;
    background-color: #ffffdd;
    border-color: Gray;
    position:absolute;
    height:100%;
    width:100%;
    top:0px;
    left:0px;
}
Image.skin:

<asp:Image SkinID="sknLoading" runat="server" ImageUrl="Images/Loading.gif" />
Attaching Loading.gif


What i am missing?? How can i resolve both problems?