500GB Passport no longer visible to Mac, works okay on PC

Mac O/S 10.4 Leopard (latest that can be installed on the old G4).

Windows XP Home with SP3


Working fine on both platforms as a large USB drive. Today it would not mount to the Mac, but still works fine on the PC. The Disk Utility on the Mac can see it and recognizes it as a 493GB External Drive, but it won’t mount. It will not complete a verify or repair, stating that the “underlying file quit too soon.”  The Mac recently had a power failure that took out the power supply, which has been replaced, and everything seems to be working fine. It’s just the Passport drive. I also have reason to believe that the drive may have been disconnected incorrectly (plug pulled without ejecting). Could that do it?  How can I restore mountability to the Passport?  I rely on it for backing up the Mac on a regular basis.


Be sure to connect the passport directly to the Mac, avoid using extension USB cables or USB hubs.