Tried out the spinrite hard disk data recovery pkg. It's produced by GRC.com. of Steve Gibson fame. I was attempting reclaim data on a failed notebook drive, for another client. Ordinarily, I'd simply try using knoppix, but I figured I'd play with spinrite.
For whatever reason, the BIOS would not recognize the drive.
Apparently, there was a problem with boot sector of the disk. Nonetheless, I figured that spinrite was worthy adversary. However, it wasn't able to either diagnose a problem or recognize the disk either. In all fairness maybe sp6.0 isn't invincible.
I also had the same high regard for Spinrite. I've got two Windows boxes showing errors with CHKDSK and assumed that Spinrite could fix these problems. Nope.
Sometimes when sectors go bad because of black-screen hard shutdowns (due to a bad video driver or a removeable optical drive in a laptop popping loose) you may need to reformat the entire system volume to "fix" the problem.
Also notebooks may have "BIOS" information on the harddrive. I am sure you are familiar with this sick irony.
Tried to use Spinrite once, asked for a refund.
Seen used and am using programs that run and run well.
and BTW CHKDSK when run is meant to hide damaged Sectors from being used it doesn't actually repair.