Why can't I run SpinRite on my hard drive?

Episode 1734 (52:50)

Don from Dana Point, CA
SpinRite by Steve Gibson

Don was using SpinRite on his computer and he's having a problem running it without a thumb drive. Leo says Windows may be getting in the way and he recommends trying a USB key that boots to FreeDos and add SpinRite onto that. You'll boot to it and then run SpinRite from there. Then you can run SpinRite on your hard drive.