Textfield not updating with SaveAs dialog
<p>For some reason, when I show the SaveAs dialog, my Checksum box never gets updated.  However, if I comment out the Content-Disposition header code below then everything works fine.  Any ideas?</p>

<pre><code>protected void SubmitButton_Click(object sender, EventArgs e)
{
    checksumField.Text = String.Empty;

    FileInfo filename = this.CreateFileInfoFromInput();

    if (!filename.Exists)
    {
        tableField.Focus();
        tableField.BorderColor = System.Drawing.Color.Red;
        return;
    }

    this.SaveFile(filename);
    checksumField.Text = GetChecksum(filename);
}

private FileInfo CreateFileInfoFromInput()
{
    /* blah */
    return new FileInfo(blah);
}

private string GetChecksum(FileInfo filename)
{
    return "test";
}

private void SaveFile(FileInfo fileName)
{
    // Clear old headers
    Response.Clear();
    Response.Buffer = false;

    // Set the ContentType and Headers
    Response.ContentType = "application/octet-stream";
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName.Name);  //  &lt;&lt;&lt;---- FAILING RIGHT HERE
    Response.AppendHeader("Content-Length", fileName.Length.ToString(System.Globalization.CultureInfo.InvariantCulture));
    Response.AppendHeader("Connection", "Keep-Alive"); 

    // Send data
    Response.TransmitFile(fileName.FullName);
}
</code></pre>
