I consider myself very good at all things Mac. But this one has me stumped. I've just arrived home with a WD My Book Home Edition 1TB external drive. Formatted for Windows it mounted correctly via FireWire and USB. First things first: I formatted it for the Mac... Mac OS Extended (Journaled), two GUID partition tables. So far so good. Each partition is recognized, each mounts like it should. Time Machine then backed up my Intel iMac... again, everything's normal. No odd or unusual behavior. Here's where things get strange. For whatever reason I formatted the drive via USB. But my intention hereafter is to connect via FireWire... I need each USB port for peripherals. But the drive isn't recognized through FireWire. I'm asked if I want to initialize it. When reconnected through USB the drive mounts again. What's going on? Why is the drive recognized when connected via USB but not when connected via FireWire?