virtualbox.org

The other VDIs are readable and I didn't change the size when I cloned the file. Let me first check the host drive before proceeding .... may take a while.

Like I said in a previous post "I'm in good hands here"! There certainly is a problem with the hard drive that the VDI resides on. I'm running some more diagnostics ... could take all day
But, thanks to you, an even bigger problem may have been averted.

Whatever happened to the drive, it did a good job of messing things up. All of the utilities I've run just crash or hang when they reach the damaged area: Seatools (it's a Seagate drive), Windows Error Check, HD Tune and others. So rather than risk a real disaster, I'm going to replace the drive - with a WD I may add. I thought about cloning the old one but this is an opportunity for me to explore the mysteries of Windows 8 so I ordered a copy for delivery with the HD (yes, I'm out in the boondocks). I'll do a brand new fresh installation and reload software as needed. As for the damaged VM, I'll make another clone of my "original" and have a clean fresh start there as well.

So, many thanks again for all your patience and assistance. It's really comforting to know that there are real professionals out there who are willing to help babes-in-the-wood like myself

You're welcome. If the damage is that extensive then I guess that repairing the header on the VDI would probably be pointless, as other areas are likely to be corrupted too. As you say, better to start from scratch, or at least start from a backup stored on secondary media before the failure.