ASP.NET

<ajax:ModalPopupExtender ID="mpePopup" runat="server"
       TargetControlID="btnPopupTargetControl"
       PopupControlID="pnlPopup"
       OkControlID="btnPopupOKControl"
       PopupDragHandleControlID="divPopup"
       BackgroundCssClass="modalBackground"
       DropShadow="true"
       RepositionMode="RepositionOnWindowResizeAndScroll"
       >
       <Animations>
           <OnShowing>
               <FadeIn Duration=".5" Fps="30" />
           </OnShowing>
           <OnShown>
               <FadeIn Duration=".5" Fps="30" />
           </OnShown>
           <OnHiding>
               <FadeOut Duration=".5" Fps="30" />
           </OnHiding>
           <OnHidden>
               <FadeOut Duration=".5" Fps="30" />
           </OnHidden>
       </Animations>
   </ajax:ModalPopupExtender>

System.Security.Principal.WindowsIdentity.GetCurrent().Name;

NT AUTHORITY\IUSR

<identity impersonate="true"/>
   <authentication mode="Windows" />
   <authorization>
     <allow users ="*" /><!-- This allows access to all users -->
   </authorization>

using System;
using System.Data;
using System.Data.OleDb;
using System.Web.UI.WebControls;

public partial class frmRegisterStudent : System.Web.UI.Page
{
    private void PopClass()
    {
        // Populate Class and add Please Select
        // Populate Student and add Please Select
        string path = Server.MapPath("eAcademy_DB.mdb");
        string connectionString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=" + path;
        string commandText10 = "SELECT class_ID FROM tblClass WHERE class_ID NOT IN (SELECT class_ID FROM tblschedule GROUP BY class_ID HAVING COUNT(class_ID) >= 10)";

        var ds10 = new DataSet();

        using (var connection10 = new OleDbConnection(connectionString))
        using (var command = new OleDbCommand(commandText10, connection10))
        {
            // OleDbCommand uses positional, rather than named, parameters.
            // The parameter name doesn't matter; only the position.
            command.Parameters.AddWithValue("@p0", ddlstudID.SelectedValue);

            var adapter = new OleDbDataAdapter(command);
            adapter.Fill(ds10);
        }

        ddlclassSelect.DataSource = ds10;
        ddlclassSelect.DataTextField = "class_ID";
        ddlclassSelect.DataValueField = "class_ID";
        ddlclassSelect.DataBind();
        ddlclassSelect.Items.Insert(0, new ListItem("Please Select", "0"));
                      
            
    }
    private void PopStud()
    {
        // Populate Student and add Please Select
        string path = Server.MapPath("eAcademy_DB.mdb");
        string connectionString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=" + path;
        //string commandText = "SELECT * from tblStudent";
        string commandText = "SELECT * FROM tblStudent where tblStudent.stud_id in (SELECT tblSchedule.stud_id FROM tblSchedule GROUP BY tblSchedule.stud_id HAVING count(tblSchedule.stud_ID) < 3)";
        var ds9 = new DataSet();

        using (var connection9 = new OleDbConnection(connectionString))
        using (var command = new OleDbCommand(commandText, connection9))
        {
            // OleDbCommand uses positional, rather than named, parameters.
            // The parameter name doesn't matter; only the position.
            command.Parameters.AddWithValue("@p0", ddlstudID.SelectedValue);

            var adapter = new OleDbDataAdapter(command);
            adapter.Fill(ds9);
        }

        ddlstudID.DataSource = ds9;
        ddlstudID.DataTextField = "stud_ID";
        ddlstudID.DataValueField = "stud_ID";
        ddlstudID.DataBind();
        ddlstudID.Items.Insert(0, new ListItem("Please Select", "0"));
        
    }
    private void CheckSession()
    {
        if (Session["SecurityLevel"] == null)
        {
            Response.Redirect("~/frmLogin.aspx");
        }

    }
    protected void Page_Load(object sender, EventArgs e)
    {
        CheckSession();

        if (!IsPostBack)
        {
            
            PopClass();
            PopStud();

        }
        else
        {
            ddlstudID.DataBind();
            ddlclassSelect.DataBind();
            
        }
    }
    protected void AddClass_Click(object sender, EventArgs e)
    {
        // Error Check so that Please Select is not there
        if (ddlstudID.SelectedValue == "0")
        {
            lblErrStudentName.Text = "Please Select a Student.";
            lblErrStudentName.Visible = true;
        }
        else
        {
            lblErrStudentName.Text = "";
            lblErrStudentName.Visible = false;
        }
        // Error Check so that Please Select is not there
        if (ddlclassSelect.SelectedValue == "0")
        {
            lblErrClassSelect.Text = "Please Select a Class.";
            lblErrClassSelect.Visible = true;
        }
        else
        {
            lblErrClassSelect.Text = "";
            lblErrClassSelect.Visible = false;
        }


        if (lblErrStudentName.Text == "" && lblErrClassSelect.Text == "")
        if (clsDataLayer.SaveSched(Server.MapPath("eAcademy_DB.mdb"),
            (Convert.ToString(ddlstudID.SelectedValue)),
            (Convert.ToString(ddlclassSelect.SelectedValue))))
        {
            txtVerifySaved.Text = "The information was saved.";
            txtVerifySaved.Visible = true;
            GridView1.DataBind(); // Refresh the bottom part.

            // Reset the index on all drop downs
            PopClass();
            PopStud();
            ddlstudID.SelectedIndex = 0;
            ddlclassSelect.SelectedIndex = 0;
        }
        else
        {
            // Make this visable to see
            txtVerifySaved.Text = "The information was NOT saved.";
            txtVerifySaved.Visible = true;
        }
    }
    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        PopStud();
        PopClass();
        ddlstudID.SelectedIndex = 0;
        ddlclassSelect.SelectedIndex = 0;
        
    }
}

<%@ Page Language="C#" AutoEventWireup="true" 
    CodeBehind="Default.aspx.cs" Inherits="sample._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Stock quote and chart from Yahoo in C#</title>
<script type="text/javascript" language="JavaScript">
    /// <summary>
    /// This function will be called when user clicks the Get Quotes button.
    /// </summary>
    /// <returns>Always return false.</returns>
    function SendRequest()
    {
        var txtSymbol = document.getElementById("txtSymbol");
        // Refresh the page.
        window.location = "default.aspx?s=" + txtSymbol.value;
        return false;
    }

    /// <summary>
    /// The functyion will be called when a keyboard key is pressed in the textbox.
    /// </summary>
    /// <param name="e">Onkeypress event.</param>
    /// <returns>Return true if user presses Enter key; otherwise false.</returns>
    function CheckEnter(e)
    {
        if ((e.keyCode && e.keyCode == 13) || (e.which && e.which == 13))
            // Enter is pressed in the textbox.
            return SendRequest();
        return true;
    }

    /// <summary>
    /// The function will be called when user
    // changes the chart type to another type.
    /// </summary>
    /// <param name="type">Chart type.</param>
    /// <param name="num">Stock number.</param>
    /// <param name="symbol">Stock symobl.</param>     
    function changeChart(type, num, symbol)
    {
        // All the DIVs are inside the main DIV
        // and defined in the code-behind class.
        var div1d=document.getElementById("div1d_"+num);
        var div5d = document.getElementById("div5d_" + num);
        var div3m = document.getElementById("div3m_" + num);
        var div6m = document.getElementById("div6m_" + num);
        var div1y = document.getElementById("div1y_" + num);
        var div2y = document.getElementById("div2y_" + num);
        var div5y = document.getElementById("div5y_" + num);
        var divMax = document.getElementById("divMax_" + num);
        var divChart = document.getElementById("imgChart_" + num);
        // Set innerHTML property.
        div1d.innerHTML = "1d";
        div5d.innerHTML="5d";
        div3m.innerHTML="3m";
        div6m.innerHTML="6m";
        div1y.innerHTML="1y";
        div2y.innerHTML="2y";
        div5y.innerHTML="5y";
        divMax.innerHTML="Max";
        // Use a random number to defeat cache.
        var rand_no = Math.random();
        rand_no = rand_no * 100000000;
        //  Display the stock chart.
        switch(type)
        {
        case 1: // 5 days
            div5d.innerHTML="5d";
            divChart.src = "http://ichart.finance.yahoo.com/w?s=" + 
                           symbol + "&" + rand_no;
            break;
        case 2: // 3 months
            div3m.innerHTML="3m";
            divChart.src = "http://chart.finance.yahoo.com/c/3m/" + 
                           symbol + "?" + rand_no;
            break;
        case 3: // 6 months 
            div6m.innerHTML = "6m";
            divChart.src = "http://chart.finance.yahoo.com/c/6m/" + 
                           symbol + "?" + rand_no;
            break;
        case 4: // 1 year
            div1y.innerHTML = "1y";
            divChart.src = "http://chart.finance.yahoo.com/c/1y/" + 
                           symbol + "?" + rand_no;
            break;
        case 5: // 2 years
            div2y.innerHTML = "2y";
            divChart.src = "http://chart.finance.yahoo.com/c/2y/" + 
                           symbol + "?" + rand_no;
            break;
        case 6: // 5 years
            div5y.innerHTML = "5y";
            divChart.src = "http://chart.finance.yahoo.com/c/5y/" + 
                           symbol + "?" + rand_no;
            break;
        case 7: // Max
            divMax.innerHTML = "msx";
            divChart.src = "http://chart.finance.yahoo.com/c/my/" + 
                           symbol + "?" + rand_no;
            break;
        case 0: // 1 day
        default:                
            div1d.innerHTML = "1d";
            divChart.src = "http://ichart.finance.yahoo.com/b?s=" + 
                           symbol + "&" + rand_no;
            break;
        }
    }
</script>    

</head>
<body>
    <form id="form1" runat="server">
    <div>
        <table width="100%" border="0" 
                 cellspacing="0" cellpadding="0">
            <tr valign="top">                                            
                <td style="font-family: Arial, Helvetica, sans-serif; 
                           font-size: 14px; color: #000; text-decoration: none;">
                    <input type="text" value="" id="txtSymbol" 
                        runat="server" onkeypress="return CheckEnter(event);" />
                    <input type="button" value="Get Quotes" 
                        onclick="return SendRequest();" />
                    <br />
                    <span style="font-family: Arial, Helvetica, sans-serif; 
                                 font-size: 11px; color: #666;">
                        e.g. "YHOO or YHOO GOOG"
                    </span>
                    <%if (m_symbol != "") {%>                        
                        <div id="divService" runat="server">
                        <!-- Main DIV: this DIV contains text and DIVs 
                                       that displays stock quotes and chart. -->
                        </div>
                    <%}%>
                </td>    
            </tr>
        </table>
    </div>
    </form>
</body>
</html>

And under Default.aspx page I have the following code:
<%@ Page Language="C#" AutoEventWireup="true" 
    CodeBehind="Default.aspx.cs" Inherits="sample._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Stock quote and chart from Yahoo in C#</title>
<script type="text/javascript" language="JavaScript">
    /// <summary>
    /// This function will be called when user clicks the Get Quotes button.
    /// </summary>
    /// <returns>Always return false.</returns>
    function SendRequest()
    {
        var txtSymbol = document.getElementById("txtSymbol");
        // Refresh the page.
        window.location = "default.aspx?s=" + txtSymbol.value;
        return false;
    }

    /// <summary>
    /// The functyion will be called when a keyboard key is pressed in the textbox.
    /// </summary>
    /// <param name="e">Onkeypress event.</param>
    /// <returns>Return true if user presses Enter key; otherwise false.</returns>
    function CheckEnter(e)
    {
        if ((e.keyCode && e.keyCode == 13) || (e.which && e.which == 13))
            // Enter is pressed in the textbox.
            return SendRequest();
        return true;
    }

    /// <summary>
    /// The function will be called when user
    // changes the chart type to another type.
    /// </summary>
    /// <param name="type">Chart type.</param>
    /// <param name="num">Stock number.</param>
    /// <param name="symbol">Stock symobl.</param>     
    function changeChart(type, num, symbol)
    {
        // All the DIVs are inside the main DIV
        // and defined in the code-behind class.
        var div1d=document.getElementById("div1d_"+num);
        var div5d = document.getElementById("div5d_" + num);
        var div3m = document.getElementById("div3m_" + num);
        var div6m = document.getElementById("div6m_" + num);
        var div1y = document.getElementById("div1y_" + num);
        var div2y = document.getElementById("div2y_" + num);
        var div5y = document.getElementById("div5y_" + num);
        var divMax = document.getElementById("divMax_" + num);
        var divChart = document.getElementById("imgChart_" + num);
        // Set innerHTML property.
        div1d.innerHTML = "1d";
        div5d.innerHTML="5d";
        div3m.innerHTML="3m";
        div6m.innerHTML="6m";
        div1y.innerHTML="1y";
        div2y.innerHTML="2y";
        div5y.innerHTML="5y";
        divMax.innerHTML="Max";
        // Use a random number to defeat cache.
        var rand_no = Math.random();
        rand_no = rand_no * 100000000;
        //  Display the stock chart.
        switch(type)
        {
        case 1: // 5 days
            div5d.innerHTML="5d";
            divChart.src = "http://ichart.finance.yahoo.com/w?s=" + 
                           symbol + "&" + rand_no;
            break;
        case 2: // 3 months
            div3m.innerHTML="3m";
            divChart.src = "http://chart.finance.yahoo.com/c/3m/" + 
                           symbol + "?" + rand_no;
            break;
        case 3: // 6 months 
            div6m.innerHTML = "6m";
            divChart.src = "http://chart.finance.yahoo.com/c/6m/" + 
                           symbol + "?" + rand_no;
            break;
        case 4: // 1 year
            div1y.innerHTML = "1y";
            divChart.src = "http://chart.finance.yahoo.com/c/1y/" + 
                           symbol + "?" + rand_no;
            break;
        case 5: // 2 years
            div2y.innerHTML = "2y";
            divChart.src = "http://chart.finance.yahoo.com/c/2y/" + 
                           symbol + "?" + rand_no;
            break;
        case 6: // 5 years
            div5y.innerHTML = "5y";
            divChart.src = "http://chart.finance.yahoo.com/c/5y/" + 
                           symbol + "?" + rand_no;
            break;
        case 7: // Max
            divMax.innerHTML = "msx";
            divChart.src = "http://chart.finance.yahoo.com/c/my/" + 
                           symbol + "?" + rand_no;
            break;
        case 0: // 1 day
        default:                
            div1d.innerHTML = "1d";
            divChart.src = "http://ichart.finance.yahoo.com/b?s=" + 
                           symbol + "&" + rand_no;
            break;
        }
    }
</script>    

</head>
<body>
    <form id="form1" runat="server">
    <div>
        <table width="100%" border="0" 
                 cellspacing="0" cellpadding="0">
            <tr valign="top">                                            
                <td style="font-family: Arial, Helvetica, sans-serif; 
                           font-size: 14px; color: #000; text-decoration: none;">
                    <input type="text" value="" id="txtSymbol" 
                        runat="server" onkeypress="return CheckEnter(event);" />
                    <input type="button" value="Get Quotes" 
                        onclick="return SendRequest();" />
                    <br />
                    <span style="font-family: Arial, Helvetica, sans-serif; 
                                 font-size: 11px; color: #666;">
                        e.g. "YHOO or YHOO GOOG"
                    </span>
                    <%if (m_symbol != "") {%>                        
                        <div id="divService" runat="server">
                        <!-- Main DIV: this DIV contains text and DIVs 
                                       that displays stock quotes and chart. -->
                        </div>
                    <%}%>
                </td>    
            </tr>
        </table>
    </div>
    </form>
</body>
</html>