Use the following registry keys to prevent Windows from auto logon.
Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Name: AutoAdminLogon
Type: REG_SZ
Value: 1 enable auto logon
Value: 0 disable auto logon
Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Name: DefaultUserName
Type: REG_SZ
Value: account to logon automatically (for example: Administrator)