Apparently, if you take a working win 2000 computer and at any point connect a bootable dos disk (floppy, zip, etc), win 2000's standard (and repeatable) behavior is overwrite that disk's boot sector in such a way as to make it irreversibly useless for many genuine dos apps. Requiring a complete reformat to correct.
Are there any known settings, maybe registry settings, to shut this "system feature" off?