SharePoint 2010 Configuration Failed (Cannot start service SPAdminV4 on computer)

I was installing Office Web App on SharePoint server 2010 and stuck with the following error while run SharePoint Configuration Wizard.

Failed to create the configuration database.

An exception of type System.InvalidOperationException was thrown.  Additional exception information: Cannot start service SPAdminV4 on computer '.'.
I was able to solve this issue by the following:

1-   Change the computer policy options for retrieving certificate validation on a network

Click on Start-Run

Type in "GPEdit.msc" and click "OK"

Expand Computer Configuration-Windows Settings-Security Settings-Public Key Policies

Double-click "Certificate Path Validation Settings"

Click on the "Network Retrieval" tab

Check the box "Define these policy settings"

Uncheck "Automatically update certificates in the Microsoft Root Certificate Program (recommended)" and "Allow issuer certificate (AIA) retrieval during path validation (recommended"

Click on "OK"

Close out of GPEdit.msc

2- Add host file entries into the local computer host file.

·        Click on Start-Run

·        Type in "C:\Windows\System32\Drivers\Etc" and click "OK"

·        Double-click the file "Hosts"

·        Select "Notepad" as the program to open the file

·        Insert the following lines into the hosts file

§  crl.microsoft.com

§  crl.verisign.com

§  ocsp.verisign.com

§  SVRSecure-G2-crl.verisign.com

§  SVRSecure-G3-crl.verisign.com

§  www.download.windowsupdate.com

§  SVRSecure-G2-aia.verisign.com

·        Save the file and exit notepad

And Good luck with runing the configuration wizred again :)

Cannot Demoting DC from domain

I was trying to demote a domain controller but I was getting the following error


"The Operation faile because:
A domain controller could not be contacted for the domain <domain name> that contained an account for this computer. Make the computer a member of a workgroup the rejoin the domain before retrying the promotion.
"The specified domain either does not exist or could not be contacted"".

The server is not the last DC and i can ping the the other DC

Resolution:

1- Verify that the default domain controllers policy exists in Active Directory and is granting the “Enable computer and user accounts to be trusted for delegation” user right to the Administrators security group.
http://support.microsoft.com/kb/2002413

2- Make sure DNS is working, the DNS in the TCP/IP properties should contain the IP of a DC that's staying a DC, and you should check that replication is working either by viewing the Event Viewer and by forcing a replication in AD Sites and Services.

3- If you cannot get things to play well and you want to force the demotion anyway, you can use the /forceremoval switch on DCPROMO, proceed with the forced demotion, but then you'll have to do an NTDSUTIL / METADATA CLEANUP on your remaining DC(s) to remove the metadata of the old server from the active directory.
To Clean up Server Metadata: http://technet.microsoft.com/en-us/library/cc816907(v=ws.10).aspx