Error while installing Exchange 2013

Installation Fail of Exchange 2013 in PrepareAD and Setup.exe

[ERROR] Setup encountered a problem while validating the state of Active Directory: Couldn’t find the Enterprise Organization container.
[08/23/2012 16:50:04.0804] [0] The Exchange Server setup operation didn’t complete.  More details can be found in ExchangeSetup.log located in the <SystemDrive>:\ExchangeSetupLogs folder.
[08/23/2012 16:50:04.0804] [0] The registry key, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ExchangeServer\V15\Setup, was not found.
[08/23/2012 16:50:04.0804] [0] End of Setup

 More Error details from ExchageSetupLog

[08/23/2012 18:53:19.0615] [0] Setup is choosing a local domain controller…
[08/23/2012 18:53:28.0981] [0] Setup has chosen the local domain controller SRVR2012.WIN12.COM for initial queries
[08/23/2012 18:53:29.0614] [0] [ERROR] Setup encountered a problem while validating the state of Active Directory: Couldn’t find the Enterprise Organization container.
[08/23/2012 18:53:29.0614] [0] [ERROR] Couldn’t find the Enterprise Organization container.
[08/23/2012 18:53:29.0614] [0] Setup will use the domain controller ”.
[08/23/2012 18:53:29.0614] [0] Setup will use the global catalog ”.
[08/23/2012 18:53:29.0614] [0] Exchange configuration container for the organization is ‘CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=WIN12,DC=COM’.
[08/23/2012 18:53:29.0614] [0] No Exchange organization container was found for the organization. Message: ‘Couldn’t find the Enterprise Organization container.’.
[08/23/2012 18:53:29.0614] [0] Setup will search for an Exchange Server object for the local machine with name ‘SRVR2012′.
[08/23/2012 18:53:29.0723] [0] No Exchange Server with identity ‘SRVR2012′ was found.


CAUSE : 

Generally this problem occurs when unsuccessful installation of Exchange server 2013 found in Active directory Forest.

SOLUTION :

First of all  Delete the Exchange Server Folder – "C:\Program Files\Microsoft\Exchange Server."

1. Log on to the domain controller with administrative credentials.
2. Click Start, click Programs, click Administrative Tools and then click Active Directory Users and Computers.
3. In the Active Directory Users and Computers management console pane, click View from the toolbar menu and select Advanced Features.
4. In the Active Directory Users and Computers management console pane, locate the incorrect, duplicate Microsoft Exchange System Objects container or organizational unit (OU).
5. Verify the incorrect, duplicate Microsoft Exchange System Objects container or OU does not contain valid Active Directory objects.
6. Right-click the incorrect, duplicate Microsoft Exchange System Objects container or OU and then click Delete.
7. Confirm the deletion by clicking Yes in the Active Directory dialog box.
   
   
   For More information Please visit microsoft Technet website :
   http://technet.microsoft.com/en-us/library/aa998138%28v=exchg.80%29.aspx
   
   

   Now Run the setup again. :) :)