Configuration file is not well-formed XML #2

I'm trying to fix an IIS 7 web server on Windows Server 2008. I don't know what caused this configuration to go bad. Any ideas on where to begin to look?

Error when clicking on the server node in the object explorer of IIS Manager.

There was an error when trying to connect.  Do you want to retype your credentials and try again?

Details:

Filename:

\\?\C:\Windows\system32\inetsrv\config\applicationHost.config
Line number: 1
Error: Configuration file is not well-formed XML

enter image description here

Solution

Follow this, but do not copy the "schema" folder, nor the "Export" folder from the history to the current folder.

http://web.archive.org/web/20130110080607/http://jshidell.com/2012/03/27/fixing-corrupted-applicationhost-config-file-in-iis-7/

More info:

I was able to reproduce this issue!! Modifying the Web.Config incorrectly (see answer to question below) ultimately caused this issue. Because I did all of this stuff, I'm having to restore from a server backup to fix everything since it'll be too difficult to undo everything. Bad Bad Bad Microsoft!

ASP.NET Generic Handler not getting called after .NET 3.5 to .NET 4.0 upgrade

This question is related to:

https://serverfault.com/questions/525443/how-to-uninstall-iis-from-windows-server-2008/525496#525496

Lesson Learned: Before a web server deployment, copy the contents out of this folder before ever changing IIS 7 configuration or making Web.Config changes.

C:\Windows\system32\inetsrv\config\