...This release adds more explicit error messages, improvements to Internet cache deletion, rebuilding of Mail's envelope index, support for Mac OS X Server, improvements to the uninstaller, and other changes. Onyx is free (donations welcome) for Mac OS X 10.4 (Universal Binary).
OK, I did a full backup of my home folder and started Disk Utility, asking it to verify my Mac HD. Sure enough, it finds an error. Anyone have any ideas on what to do about this one? Rather an odd message! See the attached thumbnail.