If you setup a username using the "@" symbol, you will not be able to login to Windows 7. Simply changing the username will not resolve the issue. Reboot the system into Safemode and log in as an Administrator. Setup a new user account without using the "@" symbol in the name.
Look for this document to be updated by Microsoft.
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Wow, never have seen this issue in a forum, applies to XP and more
thanks..i learned something new today..most helpful information about seven(7)