Mac OS X 10.4.9: "Disk image you are opening may be damaged..." alert appears

Issue or symptom

Mac OS X 10.4.9 improves the ability of Mac OS X to detect damaged or corrupted disk images before mounting them. Mounting a damaged or corrupted disk image can result in data loss or corruption. This alert appears when you try to open or (mount) a damaged disk image:

"The disk image you are opening may be damaged and could damage your system. Are you sure you want to open this disk image?"

Solution

If you have another copy of the files that are on the affected disk image

1. Make a new image in Disk Utility and copy the original files to the new image.
2. Discard the original, affected image.
3. As a precaution, open (mount) the new image, open Disk Utility, and repair the new image. Continue to repair until no issues are found.
   
   

If you have no other copy of the files on the affected disk image

Try repairing the directory structure of your disk images with Disk Utility.

1. Make a copy of the affected image in the Finder (select it, then from the Finder's File menu choose Duplicate). A duplicate image whose name ends with "copy" will be created (you will need sufficent free disk space).
2. Open (mount) the copied disk image file in the Finder. When the alert appears, click "Open".
   
   Important: If you are unable to mount the image in the Finder, the image may be unusable. If you are able to open the image in a previous version of Mac OS X, some data may be damaged. Use the data with caution.
   
   
3. Open Disk Utility (located in the Utilities folder, within the Applications folder).
4. Select the copied disk image's icon in the left side of the Disk Utility window, then click Repair Disk. A verification will be performed and, if necessary, repairs.
   
5. Click Repair again. Repeat this step until no issues are found on the image.
   
   Note: If repairs cannot be performed because the image is read-only, convert the image to a read/write format with a new name (don't replace the existing image with a same-named image). Then perform step 4 and 5 on the converted image. After repairs are complete, you can convert the image back to a read-only format and rename it if desired.

You should now be able to use the disk image without any issues.

Additional information

It is possible for a damaged disk image to cause directory issues to your Mac OS X volume.