> The only way to return to FAT16 is to backup, and reformat.  I've never
> heard of a "logical bad sector"; all bad sector are physical.  A
> "logical bad sector" would be something like a cross-linked file or
> something.

        Not any more, partition magic and others freely allow you to swtich between
FAT16 and FAT 32, and back again.

>      Can a virus be the cause of bad clusters ? Thanks for
>      answering in
>      advance.
>
> No, as far as I know, viruses cannot affect hardware.  Can anyone
> correct me?

        True, viruses usually cannot affect hardware, however, many of the smarter
viruses out there use bad sectors to their advantage. What they do is mark a
sector bad, so DOS will stay away and put something else there, some of the
boot record moving viruses do that, they move their code into the boot
record's spot and move the boot record to a "bad sector" on the disk. TTYL