Exchange 2000 System Manager service will not start.

Background:
Server running:  Windows 2000 small business server SP4
                         Exchange 2000 SP3

Problem:
The exchange 2000 SYSTEM ATTENDENT service will not start. When i try to start the service manualy the following message is displayed.

"Could not start the Exchange System Attendant serice on the local computer. The service did not return an error. This could be an internal Windows Error or an internal service arror If the problem persists contact administrator."

In Event Viewer i can see the following errors:

Source: MS ExchangeSA   Category: General  Event ID: 1005
Description:
Unexpected error. The specified domain either does not exist or could not be contacted. Facility: Win32 ID no: c007054b Microsoft Exchange System Attendant occurred.

Microsoft support suggests to:

Check DNS Settings on the Server and ensure that they are correct.   DONE
(I am not experienced with DNS but the server points to its own IP address in the DNS settings of the NIC properties. previously the server has worked fine with this setup)

Ensure that the System Attendant Service is starting with the Local System Accountant.     DONE
Ensure that the Exchange Domain Servers Global Security Group is present in the USERS Container.   DONE
Ensure that File and Print Sharing and NetBIOS over TCP/IP are not disabled.   DONE
Ensure that the TCP/IP Helper Service is not disabled.    DONE

Does Any one have any ideas on how to fix this? It is Fairly urgent as the server is not send\receive emails at all.

Thanks