MSExchange AD toplogy service errors after installing CAS

I installed CAS into the exchange 2007 organization and the installation failed with "Microsoft Exchange Active Directory Topology Service" service start up error. Event viewer is continuously throwing below errors.

 Event Type:      Error
Event Source:      MSExchange ADAccess
Event Category:      Topology
Event ID:      2114
Date:            7/7/2009
Time:            7:04:22 PM
User:            N/A
Computer:      MYCAS1
Description:
Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=1340). Topology discovery failed, error 0x80040a02 (DSC_E_NO_SUITABLE_CDC). Look up the Lightweight Directory Access Protocol (LDAP) error code specified in the event description. To do this, use Microsoft Knowledge Base article 218185, "Microsoft LDAP Error Codes." Use the information in that article to learn more about the cause and resolution to this error. Use the Ping or PathPing command-line tools to test network connectivity to local domain controllers.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

I did a little bit of googling and few blogs/forums are suggesting to add exchange server account o "Domain Admins" computer group and look like this worked for most of the people.

I am trying to install Exchange 2007 on Windows 2008 SP2 R2 server.