Error when generate excel in ax 2009

Hi all,

 I am trying to generate excel in ax 2009(Chinese version). I have created a form and use the menuItemButton to call the class to generate the excel.

It works fine when generating the excel without open then close other folders/word Pad... and close it

But when generating the excel and open then close other folders/word Pad, it will flow error ("类“Range”的 COM 对象中的方法“value”返回了错误代码 0x800A03EC (<未知>)，此错误代码表示: <未知>。"/ "执行代码时出错。: 变量赋值中的参数类型错误。" / "提供的参数数目与该方法接受的参数数目不同。")

 Does anybody also try this error before?

Thank you.