But, if you WANT an alert window, you can just use a literal Web control
like so:

<asp:Literal id="ltlErrMsg" runat="server" />

And then set its Text property to the appropriate JavaScript code:

ltlErrMsg.Text = "<script language=""JavaScript"">" & vbCrLf &
"alert(""Hello, World!"");" & vbCrLf & "<" & "/script>"