This is actually caused by visiting the administration tool (by going
to the website menu and click on asp.net configuration). and that
automatically changed the configuration tab to:
configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
work around steps:
Change in WebAdminPage.cs file, located in
%windir%\Microsoft.NET\Framework\v2.0.50727\ASP.NETWebAdminFiles\App_Code
directory, the line (number 93):
config.NamespaceDeclared = true;
with
config.NamespaceDeclared = false;
so next time when u go to admin tool the config tag will not be changed automatically anymore.