GeekLAN

Due to a lack of disk space I decided to zap my /System & /Library folders while my PowerBook was in Target Disk mode & connected to my G4 PowerMac, only to find out that I couldnt install Tiger when I got the PowerBook home
Running Disk Utility & trying to repair the disk brought up several Overlapped Extent Allocation Errors (File 123465x)

After laying a few bricks here & there as I hadn’t backed up (surprise! surprise!!!) I googled around & came up with this

As Keoneo mentions in the 3rd tip, if you make a note of the file numbers DiskUtility complains about, fire up terminal.app & run find / -inum 123456 (dont worry about any of the letters at the end of the file number)
You’ll be given the file name of the offending file number, unfortunately you cant actually delete the individual file, you have the delete the folder which the file is in by typing the following command in terminal.app rm -rf /path/to/offending/file/
If you are doing all this from the OS X install Disk or if you have connected the broken disk/System to a healthy Mac add /Volumes/*disk_label*/ to the beginning of the path e.g if your broken disk is called "Macintosh HD" you would issue the follwing command
rm -rf /Volumes/Machintosh\ HD/path/to/offending/file/
note the backslash between the word Macintosh & HD, you need to have that in so the shell understands that whatever you are referring to has a space in otherwise it treats the text either side of the space as two seperate things which wont work!!
Once you have removed the offending files, run repair disk in Disk Utility again & all should be well again!!

Verify and Repair disk "Macintosh HD"
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Incorrect number of thread records
Checking Catalog hierarchy.
Checking Extended Attributes file.
Checking volume bitmap.
Volume Bit Map needs minor repair
Checking volume information.
Invalid volume file count
(It should be 29573 instead of 466435)
Invalid volume directory count
(It should be 5662 instead of 80007)
Invalid volume free block count
(It should be 5920335 instead of 1269081)
Volume Header needs minor repair
Repairing volume.
Rechecking volume.
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Checking Catalog hierarchy.
Checking Extended Attributes file.
Checking volume bitmap.
Checking volume information.
The volume Macintosh HD was repaired successfully.
Mounting Disk

1 HFS volume checked
Repair attempted on 1 volume
1 HFS volume repaired