I have a Superdrive taken out of a MBPro. It is in an Ext casing with USB cable connection. I Have been using it connected to my iMac for months without problems. Today i put a blank DVD into it and clicked on - Open in Finder - as always. It comes up with a message saying " The operation cant be completed because you don't have the necessary permissions " I have tried everything i can think of to get round this but without success. Has anyone had this experience or have suggestions about how i can get it to work again. Thanks.