I have an external hard drive loaded with pics from various vacations, undergraduate documents, family movies, ect.. The format on the external drive is in windows format (NNT?). Therefore it can read the info on my MAC but it can't transfer new info from the MAC to the external drive. So, I took all the data and put it on my MAC, then reformatted the external drive with time machine. I then transferred all the important files back on the external drive. Once all the data...