ASP.NET application does not work: 0x80070021. This configuration section cannot be used at this path

After reinstalling the Windows, Suite ASP.NET application does not work: 0x80070021. This configuration section cannot be used at this path

Unexpectedly help comes from Microsoft Knowledge Base:

http://support.microsoft.com/kb/942055/

See case #9

http://learn.iis.net/page.aspx/145/how-to-use-locking-in-iis-70-configuration

Editing the %windir%\system32\inetsrv\config\applicationHost.config helped.

Error message:

HTTP Error 500.19 - Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid.

Detailed Error Information

Module	AnonymousAuthenticationModule
Notification	AuthenticateRequest
Handler	PageHandlerFactory-ISAPI-2.0-64
Error Code	0x80070021
Config Error	This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault="Deny"), or set explicitly by a location tag with overrideMode="Deny" or the legacy allowOverride="false".
Config File	\\?\C:\Dev\531Patch00\Root\Web\Logon\web.config

SQL 2008 setup error: Rebuild the performance counters of a SQL Server 2005 or 2008 instance

It happens if you changed the language of your system using MUI.

Here are the pills:
http://www.sqldev.org/sql-server-setup--upgrade/error-on-install-performance-counter-registry-hive-consistency-check--statusfailed-89399.shtml

Importance of order

Hi.
Just what I understand while trying to update a super-customized database came from client to our newest version:
There can never be too much journaling and logging!!!
Every megabyte you spent for detailed history of your application life can save you hours of your life those you'll damn hundred times otherwise.
Think early :-)