Jim's computer drive can't be read by Windows, but it can be seen by a Mac as read only. He can see it on a friend's windows machine, too. If he plugs it in, it asks if he wants to format the drive. Leo says there's a software error that is preventing the computer to read it. The good news is that it can be fixed, but it's often too expensive to go to a specialist. GRC's SpinRite is a good utility but it's also not cheap. It does work if he absolutely needs the data. If he can do without that data, it's probably easier to just get a new hard drive.