C#:全局鼠标事件处理程序只触发一次

我使用的是最初发布的全局鼠标事件处理程序 here .

原始问题中发布的代码运行得非常好,只是由于某种原因,当我使用它时,它只被触发了一次(之后,它再也不会被触发。)

// Subscribe to Event, (placed this in constructor)
MouseHook.Start();  
MouseHook.MouseAction += new EventHandler(Event);

// ...

// This function only gets triggered once
private void Event(object sender, EventArgs e)
{
   // Do something
}

但是,通过一些实验,我确实让它工作了,所以每次鼠标点击都会触发它(不仅仅是第一次)。

private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
    if (nCode >= 0 && MouseMessages.WM_LBUTTONDOWN == (MouseMessages)wParam)
    {
       MSLLHOOKSTRUCT hookStruct = (MSLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(MSLLHOOKSTRUCT));  
       MouseAction(null,new EventArgs());
    }
    return CallNextHookEx(_hookID, nCode, wParam, lParam);
}

对此:

private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
    if (nCode >= 0 && MouseMessages.WM_LBUTTONDOWN == (MouseMessages)wParam)
    {
       MSLLHOOKSTRUCT hookStruct = (MSLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(MSLLHOOKSTRUCT));  
       MouseAction(null,new EventArgs());

       // Added these two lines, works perfectly now
       stop();
       Start();
    }
    return CallNextHookEx(_hookID, nCode, wParam, lParam);
}

有人能解释一下:

1. 为什么我一开始就遇到这个问题
2. 上面显示的“变通方法”有效吗?