Open regedit
and navigate to HKLM/Software/Microsoft/Windows NT/Winlogon
.
Make sure to set the following keys
DefaultDomainName = YourDomain (REG_SZ)
DefaultUserName = YourUser (REG_SZ)
DefaultPassword = YourPassword (REG_SZ)
AutoAdminLogon = 1
Save, quit and reboot. Voilà