How to change the user name and the logon name for a user record in Microsoft Dynamics CRM

If you change the logon name of a Microsoft Dynamics CRM user record in Active Directory, Microsoft Dynamics CRM can no longer use the logon name to locate the user in Active Directory. Therefore, the Microsoft Dynamics CRM user cannot log on to Microsoft Dynamics CRM.

To make sure that a user can successfully log on to Microsoft Dynamics CRM, change the user name and the logon name for the user record in Microsoft Dynamics CRM. To do this, follow the appropriate steps.

Microsoft Dynamics CRM 4.0

1. Modify the user account in Active Directory. For example, change the user name, and then change the logon name.
2. Open Microsoft Dynamics CRM 4.0 as a System Administrator user.
3. Click Settings, click Administration, click Users, and then open the user record that you want to change.
4. In the Domain Logon Name box, type an Active Directory user account that is not used by a Microsoft Dynamics CRM 4.0 user record.
   
   Note If all the Active Directory user accounts are used by Microsoft Dynamics CRM 4.0 user records, create a temporary Active Directory user account.
5. Click Save.
6. In the Domain Logon Name box, type the Active Directory user account. Then, click Save and Close. 
   
   Note The Active Directory user account that you type in this step is the account that is used by a Microsoft Dynamics CRM 4.0 user record. The Microsoft Dynamics CRM 4.0 user record is the record for which you want to change the user name and the logon name in Microsoft Dynamics CRM 4.0.

Source: http://support.microsoft.com/kb/930853