Uses C# to call an Win32 API to lock the computer

Lock-Computer.ps1

<#	
	.NOTES
	===========================================================================
	 Created with: 	SAPIEN Technologies, Inc., PowerShell Studio 2016 v5.2.117
	 Created on:   	3/25/2016 17:33
	 Created by:   	Colin Squier <hexalon@gmail.com>
	 Filename:     	Lock-Computer.ps1
	===========================================================================
	.DESCRIPTION
		Uses C# to call an Win32 API to lock the computer
#>

$code = @"
using System;
using System.Runtime.InteropServices;

public static class LockDesktop
{
    [DllImport("user32.dll", EntryPoint = "GetDesktopWindow")]
    private static extern IntPtr GetDesktopWindow();

    [DllImport("user32.dll")]
    private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

    [DllImport("user32.dll", EntryPoint = "LockWorkStation")]
    private static extern IntPtr LockWorkStation();

    private const int SC_SCREENSAVE = 0xF140;
    private const int WM_SYSCOMMAND = 0x0112;

    public static void SetScreenSaverRunning()
    {
        SendMessage(GetDesktopWindow(), WM_SYSCOMMAND, SC_SCREENSAVE, 0);
        LockWorkStation();
    }
}
"@

Add-Type -TypeDefinition $code

[LockDesktop]::SetScreenSaverRunning()