I have a Toshiba external hdd that I gave someone to use on a macbook. He formatted the hdd and changed the original NTFS to a file system compatible with mac os in order to use it. He later got his own hdd and returned the Toshiba one. Problem is I now can't use the hdd on some devices. For instance, when i plug it into Sony Bravia's USB play, it says "This USB device cannot be read." However, My computer (windows 7) reads the hdd perfectly well, but there are some hidden files showing in some folders, i presume due to the mac file system. I would like to revert the hdd to a file system that can be read by other devices, like my tv, other than my computer, if possible. Thanks.