If the blocking message shows the wrong user ID and the user is on Windows 7, it is most likely a cached user ID issue.
Please check the following:
- Open User Accounts by clicking the Start button, and selecting Control Panel and then User Accounts.
- In the left pane, click Manage your credentials.
- If the user has any entries under Windows Credentials, remove these stored/cached IDs.
Open a new browser, and the user should now be utilizing his normal Windows domain logon.