Backup/restore via diskutility: error

Question

I´ve been following the instructions below to the last letter trying to backup and restore my Macbook pro osx 10.6.3 via disk utility. When trying to restore, all I get is this error:
"Could not validate source. Bad file descriptor."
I can see from other postings that I am not the only one with this problem, but so far I haven´t seen a solution. Can anybody help?
Raymond
Instructions followed:
Instructions for backing up to an external hard disk via Disk Utility
1 Connect an external hard drive (FireWire or USB) that has sufficient free space to hold at least one copy of the contents of your Macintosh HD.
2 Start from your Mac OS X 10.5 or 10.6 Install DVD. (Insert the disc, then restart and hold the C key.)
3 Select your language. Do not start an installation.
4 Choose Disk Utility from the Utilities menu.
5 Select the disk you wish to back up (your source disk, such as Macintosh HD) in the source pane on the left.
6 Click the "New Image" button in the toolbar.
7 Give your image a useful name such as "04-15-2009 Macintosh HD backup". A date in the name makes it easy to tell when the backup was made.
Note: For additional security, you can encrypt the backup disk image. From the "Encryption:" pop-up menu, select either 128-bit or 256-bit AES encryption. When prompted enter a password for the encryption: Use the password assistant to help you make a good password, or see this link for information about how to choose a good password.
8 Be sure the Save destination is a location on your external hard disk, then click "Save" to continue.
9 Enter your admin name and password if prompted. The imaging process will begin. The time it takes to complete the imaging process depends on factors such as the amount of data on your Macintosh HD. Approximately 1 GB per minute will be imaged, depending on various factors.
10 When the process is complete, quit Disk Utility (press Command-Q).
11 Press Command-Q to quit the Mac OS X installer; you will be prompted to restart.
Restoring the backup disk image's contents to your internal Mac OS X disk
Note: If the Mac you are restoring to is not the same Mac you used to make the backup disk image, use Migration Assistant instead of Disk Utility to properly transfer the data back to your Mac.
Important: These steps will overwrite data with the same name in the same location, such as files on your desktop and in your Home folder.
1 Connect the external disk you've backed up to.
2 Start from your Mac OS X 10.5 or 10.6 Install DVD. (Insert the disc, then restart and hold the C key.)
3 Select your language. Do not start an installation.
4 Choose Disk Utility from the Utilities menu.
5 Select your internal Mac OS X disk that you want to restore to.
6 Click the Restore tab.
7 Drag your internal disk to the "Destination:" field.
8 Click the "Image..." button next to the "Source:" field.
9 Navigate to the location of the backup image you want to restore (located on your external disk).
10 Click "Open" to continue.
11 Click the "Restore" button. Confirm you want to "Restore to Disk" by clicking "Restore" again. This will replace data on your Mac OS X volume with data from your backup that has the same name and is in the same location.
12 Enter your admin name and password when prompted. If the backup disk image is encrypted, enter the disk image password if necessary. The time it takes to restore from the image depends on factors such as the amount of data on your backup disk image.

Answer 1

Hi Raymond,
The first thing I would try , after step 4 and before step 5 in the "restore" component of the process you list, would be to:
4a) Select the hard disk you wish to restore FROM in the left hand panel of Disk Utility
4b) use the "First Aid" tab in Disk Utility to "Repair Disk"
4c) Repeat the same repair process, but this time select the .dmg file in the left hand panel.
If it comes up with things that can't be repaired, post back, but otherwise then try following through steps 5 etc.
Cheers
Rod