unable to start sap mmc

I have upgraded my OS from server 2003 to server 2008r2. Unfortunately i have deleted my sap mmc instances and when i re configured them again i am getting the below error message.

WebService error: 20

Unknown error

TCP connect failed in tcp_connect()

DCOM Interface error: 8007042D

The service did not start due to a logon failure.

Can anyone please suggest the solution for this.

Thanking you inn advance