Diskutil says "HasFolderCount flag needs to be set" a thousand times?

[michaelsanford]

I've been using an external drive with my (previous) 10.4 installation and backed up another 10.3 home folder.

I was just about to enable Time Machine on it, and thought it would be a good idea to run a Repair Disk from Disk Utility first. However, I get this as a return:

Verify and Repair volume “Castor”
Checking Journaled HFS Plus volume.
Detected a case-sensitive catalog.
Checking Extents Overflow file.
Checking Catalog file.
Checking multi-linked files.
Checking Catalog hierarchy.
HasFolderCount flag needs to be set (id = 2)
(It should be 0x10 instead of 0)
HasFolderCount flag needs to be set (id = 18)
(It should be 0x10 instead of 0)
HasFolderCount flag needs to be set (id = 21)
(It should be 0x10 instead of 0)
...

A million times, with different "id =". I left it for two hours and it was still going. The highest number I got up to was (id = 576097).

Sometimes the explanation is "Should be 4", or 2 or 1 or a few others.

What is this error? Should I just leave it overnight and let it run its course?

Thanks!