If a username has been changed on a system, Remote Desktop sessions into that computer cannot login with the new username. The old username and password still work.

Consider the following scenario:

1. Install Windows 7 on two systems
2. Setup both systems with a password
3. On the host system, in the remote tab of system properties, select “Allow connections from computers running any version of Remote Desktop”
4. On the host system, change the username and restart
5. On the client system, open the Remote Desktop Connection application and enter the computer name of the host system
6. When prompted, enter the new username and password of the primary user account on the host system. Note that you are unable to connect
7. Enter the old username and password. You are now able to connect

Considering the following scenario:

• On a Windows Vista-based or Windows Server 2008-based computer, you are running a client application that must connect to a server application. For example, you are running a Microsoft SQL Server client, a Microsoft Internet Security and Acceleration (ISA) Server client, or a Microsoft Office Excel client.
• The computer that hosts the client application is in a workgroup or in a different domain from the domain that hosts the server application.
• On the client computer, you have stored the domain credentials in Credential Manager.
  Note: You can use the Stored User Names and Passwords feature in Control Panel to store credentials.

In this case, the client application that has to obtain domain credentials from Credential Manager cannot connect to the server application in the domain.

For example, assume that you store the domain credentials of an authenticated user in Domain A on a Windows Vista-based computer. This computer is in a workgroup. In this example, when you open SQL Server Management Studio, and you try to connect to a SQL Server installation in Domain A, you receive an error message that resembles the following:

The user is not associated with a trusted SQL Server Connection

Note: This issue does not occur on a Windows XP Service Pack 2 (SP2)-based computer.

Consider the following scenario:

• In an Active Directory Domain Services (AD DS) environment, you apply the Allow user name hint Group Policy setting to the Windows Vista-based or Windows Server 2008-based client computers. This Group Policy setting displays the domain name when a user enters the user name.
• A user uses a Smart Card certificate for authentication during logon.
• The Smart Card certificate has a subject name that is presented in the fully distinguished name (also known as DN) format. Additionally, the domain component of the subject name does not match the domain in the network.

In this scenario, when the user tries to join the domain from a Windows Vista-based or Windows Server 2008-based client computer by using the Smart Card certificate, the user cannot join the domain. This problem occurs even though the name of the domain that the user tries to join is presented by the hint. In this case, the user receives the following error message:

The following error occurred attempting to join the domain Domain_Name:
The specified username is invalid.

On a Windows Vista-based or a Windows Server 2008-based computer, you try to establish a connection to in order to access a local network. If the user name of the user account contains Unicode characters, the connection attempt fails the Extensible Authentication Protocol (EAP) authentication. Therefore, you cannot access the local network.

Consider the following scenario:

• A domain member computer is running Windows Vista, Windows Server 2003, or Windows XP.
• On the domain member computer, an application calls the LsaLookupSids function to translate a security identifier (SID) to a user name.
• The user name has been changed on a domain controller.

In this scenario, the LsaLookupSids function may return the old user name instead of the new user name. This behavior may prevent the application from working correctly.

You try to open a 2007 Microsoft Office document that is on a shared folder, or you try to save a 2007 Office document to a shared folder. When you do this, you are prompted two times to type your username and your password to access the shared folder.

When you try use Windows Easy Transfer to transfer files and settings from a Microsoft Windows-based computer to a Windows Vista-based computer, the user name and password are not transferred.