When Windows NT is running on a computer that no user is logged on to, a dialog box appears, prompting you to press CTRL+ALT+DEL to log on. This dialog box and other aspects of the Windows NT environment at this point, such as the screen's background color and its use of wallpaper and screen savers, are controlled by the system default profile. The settings for this profile are stored in System32\config\default. The system default profile can be changed by using either Windows NT Registry Editor (Regedt32 or Regedit) to edit the Default key in HKEY_USERS.
For information about using Windows NT Registry Editor, see Part 5, "Windows NT Registry."