I would suspect an issue too, sooner or later. Use on PS3, Mac, and PC, see, what I'm getting at here. On top of all that you have a full partition already, right. I suggest you have 1 partition period on the ext. HD and make that Fat32 and be done from the PC. I also suggest you use the HP USB formatter which seems to handle most USB based drives. There simply maybe too much expected or going here and a fresh start maybe best to start again and retry.