DOS is fairly fussy about where it wants its partitions. If I were you, I'd make a small DOS partition with DOS (how large is this supposed to be? Beware of the ~510MB/1024 cylinder BIOS problems), install DOS onto it, and then install Debian elsewhere on the hard drive using Linux's fdisk to make your new partitions.
-- Regards, | Debian GNU/ __ o http://www.debian.org . | / / _ _ _ _ _ __ __ Randy | / /__ / / / \// //_// \ \/ / ([EMAIL PROTECTED]) | /____/ /_/ /_/\/ /___/ /_/\_\ http://www.golgotha.net | ...because lockups are for convicts...