Thanks Dave. I'll study the options outlined in the thread you offer.
The 16 MB FAT partition is the "Data" drive that shows up in both DOS and XP. I use it to transfer data between operating systems (program outputs like graphs or tables).
I really have only one program left that requires DOS (and a parallel port security key). It is the electronic filter design program S/FILSYN. The good news: An XP version of that program was recently released to the public domain. I'll get a copy of that -- so my future visits to DOS will be much less frequent. That said, I can probably live with the CMOS setup method of booting DOS from now on.
Still, I would like to get DOS booting and working correctly, including CD/DVD. Who knows when I might want to grab some legacy DOS/Win3.1 game CD and play around? Could there be a motherboard BIOS problem running the old DOS CD driver?
On the AUTOEXEC.BAT file: It's funny that it would appear hidden/system when viewed from XP but not from DOS. It's just an open/editable ascii text file there. Wasn't there something about BootMagic requiring entries in AUTOEXE2 instead of AUTOEXEC.BAT? The DOS drive is from a system that had BootMagic installed but it is set to inactive now. Why can't I uninstall PartitionMagic/BootMagic from DOS? I get that error message listed in previous post.
-Lee