Here is a simple 4D code snippet to lock the screen of a Windows computer:

// lock workstation on Windows If (Folder separator="\\")    $cmd:="cmd.exe /c rundll32.exe user32.dll, LockWorkStation"    LAUNCH EXTERNAL PROCESS($cmd) End if

This code can be used to secure the machine and force the user to use CTRL+ALT+DEL to unlock it (assuming a password is enabled on the OS).