User profile folder name is displayed incorrectly
Microsoft has released a new hotfix that resolves the issue of displaying a user profile folder name as “user name@domain name” when using a user principal name (UPN) to log on to a Windows 7-based or Windows Server 2008 R2-based client computer. This can happen when you have a client computer that is running Windows 7 or Windows Server 2008 R2 in an Active Directory domain and you enable the User must change password at next logon option for the domain users. Then, you log on to a client computer by using a user principal name (UPN) and the user profile folder is created on the client computer. In this scenario, the format of the user profile folder name is displayed as follows: user name@domain name.
This issue only occurs when you log on to a client computer for the first time. When you log on to the client computer again, the user profile folder is in the correct format as expected. To apply this hotfix, you must be running Windows 7 Service Pack 1 (SP1) or Windows Server 2008 R2 SP1.
Read more and download the fix from here: http://support.microsoft.com/kb/2748437/en-us?sd=rss&spid=14134