I've been having this problem for a few months now. I recently built my own computer, having been on a lap top for a couple of years, and found my old external hard drive. I plugged it in to the new computer, and it said something about needing to be formatted, which I promptly did due to nothing of importance being on it. I went to sleep, and woke up to see that it couldn't be formatted. This is where my issue begins. It no longer appears in Computer, or Disk Management. Disk Management won't even load if I have the drive plugged in. There seems to be no way at all to format the drive, since Computer, and Disk Management both don't load when the drive is plugged in. Any help?