Jonathan plugged in an external drive but he can't see it on his Mac. It wants it to re-initialize. Leo says it could be a host of things from the drive, to the cable, to the USB port, to even a software error. So he'll have to break it down. First, unplug the drive and plug it into a new port. If he's using a USB hub, try directly into the computer instead. Make sure if it's a powered drive that it's getting power. Jonathan can run Disk Utility on the Mac and see if it sees the drive. If he sees it there, then that means that the drive is starting to fail or the formatting is corrupted. Or, the table of contents is corrupted and as such, it doesn't know where the data is. The fact is, the larger the drive, the more vulnerable it can be. Bottom line though, sometimes a hard drive just fails. A certain percentage do every year. Even if they're six months old.