From Apple’s KB:
Disk Utility reports \Underlying
... In rare circumstances, Disk Utility may display the following message when you try to repair a disk:
"The underlying task reported failure"
The Disk Utility log will also display a -9972 error code. This indicates that your disk volume has issues that Disk Utility cannot fix.
What can I do?…
…. For Mac OS X 10.4.6 or earlier: If you have Adobe Photoshop CS2 or Adobe Illustrator CS2 installed, try removing the following files:
* /Applications/Adobe Photoshop CS2/Legal.localized/Tie??ng Vie??t.html
* /Applications/Adobe Illustrator CS2/Legal.localized/Tie??ng Vie??t.html ...
Basically this error means you’re probably doomed and should have good backups. Note, however, the curious Adobe related bug. I bet that one’s quite interesting.