Compilez ce fichier dans Visual Studio ou C# Express et lancez-le à partir d'une invite de commande (ou double-cliquez dessus). Nécessite .NET 4.0 ou supérieur. Il fait tout ce que vous cherchez. 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Threading;
using System.Runtime.InteropServices;
using System.Windows.Forms; 
namespace ImWorkin
{
    class Program
    {
        [FlagsAttribute]
        public enum EXECUTION_STATE : uint
        {
            ES_SYSTEM_REQUIRED = 0x00000001,
            ES_DISPLAY_REQUIRED = 0x00000002,
            ES_CONTINUOUS = 0x80000000
        }
        public SYSTEMTIMEOUTS TimeOuts
        {
            get { return sysTimeouts; }
        }
        public struct SYSTEMTIMEOUTS
        {
            public int BATTERYIDLETIMEOUT;
            public int EXTERNALIDLETIMEOUT;
            public int WAKEUPIDLETIMEOUT;
        }
        [DllImport("USER32.DLL", CharSet = CharSet.Unicode)]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
        [DllImport("USER32.DLL")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        static extern EXECUTION_STATE SetThreadExecutionState(EXECUTION_STATE flags);
        [DllImport("user32.dll", SetLastError = true, EntryPoint ="SystemParametersInfo")]
        internal static extern int SystemParametersInfo(int uiAction, int uiParam, ref int pvParam, int fWinIni);
        private static System.Threading.Timer preventSleepTimer = null;
        public const int SPI_GETBATTERYIDLETIMEOUT = 252;
        public const int SPI_GETEXTERNALIDLETIMEOUT = 254;
        public const int SPI_GETWAKEUPIDLETIMEOUT = 256;
        public static int Counter = 0;
        public static int timeOutinMS = 0;
        public static int batteryIdleTimer;
        public static int externalIdleTimer;
        public static int wakeupIdleTimer;
        public static SYSTEMTIMEOUTS sysTimeouts;
        static void Main(string[] args)
        {
            Console.WriteLine("You are about to be workin!! Just a moment...I need to calculate a few values.");
            string dots = string.Empty;
            for (int i =2; i < 60; i++)
            {
                dots = "";
                for (int ii = 0; ii < i; ii++)
                {
                    dots = dots + ".";
                }
                Thread.Sleep(100);
                Console.Clear();
                Console.WriteLine("You are about to be workin!! Just a moment...I need to calculate a few values.");
                Console.WriteLine(dots);
            }
            GetSystemTimeOuts();
            if (timeOutinMS < sysTimeouts.BATTERYIDLETIMEOUT)
                timeOutinMS = sysTimeouts.BATTERYIDLETIMEOUT;
            if (timeOutinMS < sysTimeouts.EXTERNALIDLETIMEOUT)
                timeOutinMS = sysTimeouts.EXTERNALIDLETIMEOUT;
            if (timeOutinMS < sysTimeouts.WAKEUPIDLETIMEOUT)
                timeOutinMS = sysTimeouts.WAKEUPIDLETIMEOUT;
            if (timeOutinMS == 0)
                timeOutinMS = 30;
            DisableDeviceSleep();
            Console.WriteLine("");
            Console.WriteLine("");
            Console.WriteLine("OK. I have calculated your computers timeout periods and set the ");
            Console.WriteLine("necessary hooks. Your computer will not shut off the monitor, will");
            Console.WriteLine("show active in any chat programs,the screensaver is disabled and ");
            Console.WriteLine("the computer will not lock! Anyone looking at you eaither locally ");
            Console.WriteLine("or remotely will think you are hard at work.");
            Console.WriteLine("");
            Console.WriteLine("Now go do something fun...I got your back ;)");
            Console.WriteLine("Oh yeah....if you close this window OR press `q' in this ");
            Console.WriteLine("window you are going to have to actually work.");
            Console.WriteLine("");
            Console.WriteLine("");
            Console.WriteLine("This text will disappear in a 30 seconds. Just in case someone comes ");
            Console.WriteLine("by and reads your screen!");
            Console.WriteLine("");
            Console.WriteLine("");
            Console.WriteLine("Need custom coding? Kenneth.gore@gmail.com");
            while (Console.KeyAvailable == false)
            {
                Thread.Sleep(250);
                ConsoleKeyInfo cki = Console.ReadKey(true);
                if (cki.KeyChar == 'q')
                    break;
            }
        }
        public static void DisableDeviceSleep()
        {
           SetThreadExecutionState(EXECUTION_STATE.ES_SYSTEM_REQUIRED | EXECUTION_STATE.ES_DISPLAY_REQUIRED | EXECUTION_STATE.ES_CONTINUOUS);
           preventSleepTimer = new System.Threading.Timer(new TimerCallback(PokeDeviceToKeepAwake), null, 0, timeOutinMS * 1000);
        }
        public static void EnableDeviceSleep()
        {
           preventSleepTimer.Dispose();
           preventSleepTimer = null;
        }
        private static void PokeDeviceToKeepAwake(object extra)
        {
            Counter++;
            try
            {
                   SetThreadExecutionState(EXECUTION_STATE.ES_SYSTEM_REQUIRED | EXECUTION_STATE.ES_DISPLAY_REQUIRED | EXECUTION_STATE.ES_CONTINUOUS);
                   IntPtr Handle = FindWindow("SysListView32", "FolderView");
                   if (Handle == IntPtr.Zero)
                   {
                       SetForegroundWindow(Handle);
                       SendKeys.SendWait("%1");
                   }
                   if (Counter > 1)
                       Console.Clear();
            } 
            catch 
            {
            }
        }
        public static void GetSystemTimeOuts()  
        {
            sysTimeouts.BATTERYIDLETIMEOUT = -2;
            sysTimeouts.EXTERNALIDLETIMEOUT = -2;
            sysTimeouts.WAKEUPIDLETIMEOUT = -2;
            if (SystemParametersInfo(SPI_GETBATTERYIDLETIMEOUT, 0, ref batteryIdleTimer, 0) == 1)
                sysTimeouts.BATTERYIDLETIMEOUT = batteryIdleTimer;
            else
                sysTimeouts.BATTERYIDLETIMEOUT = -1;
            if (SystemParametersInfo(SPI_GETEXTERNALIDLETIMEOUT, 0, ref externalIdleTimer, 0) == 1)
                sysTimeouts.EXTERNALIDLETIMEOUT = externalIdleTimer;
            else
                sysTimeouts.EXTERNALIDLETIMEOUT = -1;
            if (SystemParametersInfo(SPI_GETWAKEUPIDLETIMEOUT, 0, ref wakeupIdleTimer, 0) == 1)
                sysTimeouts.WAKEUPIDLETIMEOUT = wakeupIdleTimer;
            else
                sysTimeouts.WAKEUPIDLETIMEOUT = -1;
        }
    }
}