XADM: Cannot Log On to Exchange 2000 Server Computer by Using the Correct Credentials

If you use Microsoft Outlook to connect to an Exchange 2000 server, you are prompted to provide a user name, a password, and a domain name. After you enter this information, Outlook repeatedly prompts you to provide your credentials, and you cannot connect.

Note You are not a member of the Administrators group or the Domain Admins group, but this problem is resolved if you are added to the Domain Admins group.

The computer that is running Outlook is trying to make a remote procedure call (RPC) connection through named pipes. Exchange 2000 permits users to make RPC connections through named pipes. However, you cannot connect to the Exchange 2000 server by using RPC through named pipes if you are not a member of the Domain Admins group.

To resolve this problem, make sure that you are trying to make RPC connections through Internet Protocol (IP). To do so, follow these steps:

1. Remove the ncacn_np item from the RPC_BINDING_ORDER registry value in the following registry key:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\Exchange Provider
2. Make sure that the following registry key contains the information that is listed in one of the following tables, as appropriate to your operating system:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ClientProtocols
   The following values are the core required values for Microsoft Windows XP and Windows 2000:
   
   
   Collapse this tableExpand this table

   Name	Type	Data
   (Default)	REG_SZ	(value not set)
   ncacn_http	REG_SZ	Rpcrt4.dll
   ncacn_ip_tcp	REG_SZ	Rpcrt4.dll
   ncacn_np	REG_SZ	Rpcrt4.dll
   ncadg_ip_udp	REG_SZ	Rpcrt4.dll

   
   The following values are the core required values for Microsoft Windows 98:
   
   
   Collapse this tableExpand this table

   Name	Type	Data
   (Default)	REG_SZ	(value not set)
   ncacn_np	REG_SZ	Rpcltc1.dll
   ncalrpc	REG_SZ
   ncadg_ip_udp	REG_SZ	Rpcltc3.dll
   ncacn_http	REG_SZ	Rpcltccm.dll

   
   The following values are the core required values for Microsoft Windows NT 4.0:
   
   
   Collapse this tableExpand this table

   Name	Type	Data
   (Default)	REG_SZ	(value not set)
   ncacn_np	REG_SZ	Rpcltc1.dll
   ncalrpc	REG_SZ
   ncadg_ip_udp	REG_SZ	RpcLtCcm.dll
   ncadg_ip_udp	REG_SZ	RpcLtCcm.dll
   ncacn_nb_tcp	REG_SZ	RpcLtCcm.dll
   ncacn_http	REG_SZ	RpcLtCcm.dll

For additional information, click the following article number to view the article in the Microsoft Knowledge Base: