In XP, there is a difference between the user account in the Control Panel, the users in the users and groups in the Computer Management, and the number of users seen from the Key_local_machine\sam\sam\domains\account\users\names in the registry. In the control Panel to see the least, and in the Computer Management of the users and groups in the user can see some hidden users, but for the partial through the backdoor or Trojan added to the account, in general, is only through the registry can be found.
Open registry: Start-> Run->regedit.msc
By default in the registry, we are unable to see the hidden user. Here are the steps and considerations to view the hidden users and then reopen them after you restore the hidden users
1 View hidden users.
By default. Hiding the user's view is hidden.
Only the administrator gives the administrator full control over the permissions so that we can see the hidden directories and hidden files under the Sam folder.