Here's the code to reproduce the error, I'm using VS.NET 2003:
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The frameset:
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head><title>HTMLPage1</title></head>
<frameset><frame src=WebForm2.aspx></frameset>
</html>
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The aspx page: Name it WebForm2.aspx (or change frame's src attribute)
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>WebForm2</title>
<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<asp:TextBox id="TextBox1" runat="server"
AutoPostBack="True"></asp:TextBox>
<asp:Label id="Label1" runat="server">Label</asp:Label><BR>
<asp:DropDownList id="DropDownList1" runat="server"
AutoPostBack="True">
<asp:ListItem Value="1">1</asp:ListItem><asp:ListItem
Value="2">2</asp:ListItem><asp:ListItem Value="3">3</asp:ListItem>
</asp:DropDownList>
<asp:Label id="Label2" runat="server">Label</asp:Label>
</form>
</body>
</HTML>
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The events asociated:
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Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal
e As System.EventArgs) Handles TextBox1.TextChanged
Me.Label1.Text = Me.TextBox1.Text
End Sub
Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles
DropDownList1.SelectedIndexChanged
Me.Label2.Text = Me.DropDownList1.SelectedValue
End Sub
