我在獲取MAC地址是出現"未處理COMException"異常是怎么回事，下面是我的代碼：string mac = null;            ManagementObjectSearcher query = new ManagementObjectSearcher("SELECT * FROM Win32_NetworkAdapterConfiguration");            ManagementObjectCollection queryCollection = query.Get();            foreach (ManagementObject mo in queryCollection)            {                if (mo["IPEnabled"].ToString() == "True")                    mac = mo["MacAddress"].ToString();            }            return (mac);異常出現在循環讀取的地方，好像是queryCollection.count引發的異常，該如何解決呀？