Andrew, This sounds amazingly familiar .. are you writing those diskettes in a 1.44MB drive? Even with the correct double density media I've had trouble writing double density diskettes using a 1.44MB drive. Try finding a genuine DOS 3.3 diskette, not a copy made in a 1.44MB drive. Or cut your diskette images to disk using a genuine 720K drive. That'll probably work. (I had similar problems when trying to boot a PCjr using a 720KB diskette drive. None of the diskettes I made using a 1.44MB drive worked, even with the correct media. Only diskettes made on a 720KB drive were bootable.) Mike