Open an XML file in ASP.NET

Seems to be a silly problem but I cannot get it to work. I created an aspx page which is as follows

private void Page_Load(object sender, System.EventArgs e)
{
Response.ContentType = "text/xml";
}

protected override void Render(HtmlTextWriter output)
{
// output.Write("<A>Abc</A>");

}

Up until yesterday this was working fine. Now when I try to open this page, it shows a dialog box asking me to either open or save the file. If I remove the Response.ContentType line then it shows the text "Abc" on the page, but I want to see the content as XML.

Please help.

private void Page_Load(object sender, System.EventArgs e)
{
Response.ContentType = "text/xml";
}

protected override void Render(HtmlTextWriter output)
{
output.Write("<A>Abc</A>");
}

The output line is not commented as in the first post.