ajax/master page problem

[ganesh22]

Hi,
Iam using Master Page with asp.net ajax its showin some error like this
{Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack.}
why its showing like that
and my code in button click event

 
protected void Button1_Click1(object sender, EventArgs e)
{
try
{
Response.Redirect("Default.aspx");
}
catch (Exception ex)
{
Label1.Text = ex.Message;
}
}