Harus import:
using System.Runtime.InteropServices;

Lock Computer:

[DllImport(“user32.dll”)]
public static extern void LockWorkStation();

Kemudian panggil fungsinya:
LockWorkStation();

Logoff:

[DllImport(“user32.dll”)]
public static extern int ExitWindowsEx(int uFlags, int dwReason);

Panggil fungsinya:
Logoff biasa:
ExitWindowsEx(0, 0);
Logoff force:
ExitWindowsEx(4, 0);

Reboot:
ExitWindowsEx(2, 0);

Shutdown:
ExitWindowsEx(1, 0);

Hibernate:
Application.SetSuspendState(PowerState.Hibernate, true, true);
Standby:
Application.SetSuspendState(PowerState.Suspend true, true);

Bagus kan??