Invalid extent entry, invalid block count, and invalid free block count.

Well, I need some help resolving this. The errors are in bold. I've tried running disk utility both from the startup drive and from the install disk. Neither one can fix these problems. As of yet, I have not seen any trace of corrupt or problematic files, although from experience when the drive starts getting errors, it's only a matter of time.

Here's a copy of what Disk Utility is reporting.

I'm running 10.4.11 with all updates, to the best of my knowledge.Not sure about firmware updates. Are there any firmware updates for the G5 imac? Can't seem to find a list for that, either. Anyway, this is on a G5 iMac.

START QUOTE

Verifying volume “iMac”
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
*Invalid extent entry*
*Incorrect block count for file InstallationCheck.strings*
*(It should be 0 instead of 1)*
)
Checking multi-linked files.
Checking Catalog hierarchy.
Checking Extended Attributes file.
Checking volume bitmap.
Checking volume bitmap.
*p needs minor repair",0)*
Checking volume information.
*Invalid volume free block count*
*(It should be 36255614 instead of 36255613)*
The volume iMac needs to be repaired.

Error: The underlying task reported failure on exit


1 HFS volume checked
Volume needs repair

END QUOTE

Any help would be appreciated. That being said, I can't afford to a) buy expensive programs, or b) replace the hard drive.

That being said, I do have a small external USB drive, so I just cloned my whole user directory onto it (via Carbon Copy Cloner), so at least I won't lose much data.