Got it fixed! Thank you for the responses. On the Mac drivers page listed on post #2 above, I found GCC DriveManager 7.0. It recognized the Hyperdrive FX-20 immediately and formatted it. Then it informed me the driver had been corrupted, and asked if I wanted to fix it. Heck yes! It did so, and it works very well now. I wish I had had this software when I first got the drive. I bet I could have repaired the drive before doing a full format. As it was, Apple HD SC Setup screwed up the format process and rendered it unusable without a total format. I wonder what was on that drive before...we will never know.