How to change default form name "aspnetForm" in Beta 2

Here's the responsible code for that error:

public override string UniqueID
{
      get
      {
            if (this.NamingContainer == this.Page)
            {
                  return base.UniqueID;
            }
            return "aspnetForm";
      }
}

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="TestBaseForm.aspx.cs" Inherits="TestBaseForm" %>

<%@ Register TagPrefix="LA" Namespace="MyNamespace" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <LA:BaseForm runat="server" ;
            }
        }
    }
}

As you can see, when the naming container is different from the current page (something that happens when you use a master page) the UniqueID property return "aspnetForm". this property is rendered into the name attribute that is sent to the client in the form tag. so, if you really need to, you can create your own form by inheriting from htmlform and then override the UniqueID property or the Name property (this may be a better option).