Repairing a bad boot disk...?

[TheHarbinger]

I successfully installed 10.5.6 on my Gigabyte EP45-UD3R motherboard PC. I used an external USB hard drive (partitioned as GUID) as I was having problems dual-booting with my existing XP install. I planned on creating a disk image that I'd restore onto the MBR-partitioned XP disk to solve my dual-boot problem. I'd also installed the release candidate of Chameleon 2 on the external drive.

 

Well...I booted using my Grub-DFE boot disk, then swapped to the Leopard install DVD. I launched Disk Utility and went through the choices to image the USB drive, and save the image to an existing FAT32 partition on the main hard drive. The backup churned away for about twenty minutes, then locked up. I had no alternative but to hit the reset button. When the machine rebooted, Grub-DFE couldn't see the external USB drive anymore. I took the machine through a boot with the the Leopard DVD and ran Disk Utility. DU saw the external disk, saw no problems with the disk in general, but found a lot of permission errors. I fixed them and rebooted, but Grub-DFE still wouldn't see the disk. I ended up reinstalling the OS but haven't yet attempted another re-image; when I do I won't install Chameleon beforehand.

 

Now, should I face this problem again, I'd like to know: how do I repair a corrupted GUID boot record when Disk Utility doesn't find a problem?