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UPN Box in Active Directory Users and Computers Contains Corrupted Data
Content provided by Microsoft
When you use Active Directory Users and Computers to copy a user, the UPN box next to the user name contains corrupted data instead of @UserDomainName.com. If you click the arrow next to the box, you see that the field contains the correct user principal name (UPN).
This problem occurs because the UPN attribute contains information that is not valid about the user object in Active Directory directory service. This attribute must contain UserName@UserDomainName.com. However, in this case, @UserDomainName.com is missing, which leads to the corruption. You can check this attribute by using Ldp.exe or AdsiEdit.msc.
To work around this problem, change the UPN attribute for the user object to the correct UserName@UserDomainName.com string by using Ldp.exe or AdsiEdit.exe.
To resolve this problem, obtain the latest service pack for Microsoft Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
260910 How to Obtain the Latest Windows 2000 Service Pack
Microsoft has confirmed that this is a problem in Windows 2000. This problem was first corrected in Microsoft Windows 2000 Service Pack 4.