The Glyph service department has identified instances where simply shutting down a Mac OS 10.4.x machine while FireWire drives are still mounted can result in the directory of the drive being corrupted the next time the computer boots. We are not sure what causes this, as it has been reported with many drive brands, but always on Mac OS 10.4.x. At this time, we are recommending that all Mac OS 10.4 users unmount all FireWire drives before they shut down the computer. If you are having problems with your drive relating to this problem, please call tech support.