Disk Utility disk repair fails

I'm running OSX 10.4.11 on a 12" PowerBook 1.5 GHz with 1.25 GB of RAM and an 80 GB HD.

When I run the disk Utility to Verify Disk, it ends with the message, "Error: The underlying task reported failure on exit." This happens if I run the Disk Utility from the hard drive, from the OSX installation disk or from an external hard drive.

The Repair Drive button is always grayed out no matter where I am running the disk Utility from, too.

So far, I haven't had any other unusual things with the operation, but I'm concerned that this could be an early warning of problems to come.

Has anyone else had this problem or have a clue?

I have cloned the entire hard drive onto an external drive with Carbon Copy Cloner. I know PPC systems won't boot from a USB drive, but I was considering booting from the install disk, re-formatting the drive from there and then re-installing from the external by running CCC from there. I hope someone will have a direct solution to repairing the drive without doing all of that.

I'll appreciate any clues I get for certain!