> > installboot
> 
> I did.  I reinstalled GRUB to my hard-disk from the floppy.  Still the
> same.
how does installbook work?

it puts something in first disk block which loads rest of bootloader
from blocklist wrote by installboot which points to "boot" file data.

when you install grub IMHO it places it's code on first disk block
overwriting netbsd booter. to work you will need to do backup of netbsd
bootblock to some file and set this file as secondary boot loader for
GRUB. it worked in case of lilo and windoze NT, maybe will work here