You may have a physically damaged MBR, which would suck lama, but there could be other reasons.
You could try installing Grub manually if you are feeling up to it. First, get a copy of knoppix from www.knoppix.org. If you aren't familar with knoppix, its a live linux CD, it will alow you boot up a linux system work in a graphical enviroment.
Next, boot up grub and download a copy of grub. You can get it from
ftp://alpha.gnu.org/gnu/grub/ unpack and install the files.
QUOTE
$ tar -xfvz grub-0.95.tar.gz
$ cd grub*
$ ./configure
$ make
$ make install
now type the command
grub to enter the grub prompt. Enter the following commands where root is YOUR partitions with the kernel images on it. Basically what ever contains your /boot foler or what your mount to your /boot folder.
QUOTE
grub> root (hd0,1)
grub> setup (hd0)
grub> quit
Last you will have to configure your
/boot/grub/grub.conf Mount your linux drives if you haven't already. And get to your /boot/grub folder. Next, edit your grub.conf file using what ever editor you want (you will probably have to open it as root in order to edit it, type su in a termial in Knoppix to become root)
A basic grub.conf file looks something like this.
CODE
#
# Sample boot menu configuration file
#
# Boot automatically after 30 secs.
timeout 30
# By default, boot the first entry.
default 0
# For booting GNU/Linux
title GNU/Linux
root (hd1,0)
kernel /vmlinuz root=/dev/hdb1
initrd /initrd.img
# For booting Windows NT or Windows95
title Windows NT / Windows 95 boot menu
rootnoverify (hd0,0)
makeactive
chainloader +1
# For loading DOS if Windows NT is installed
# chainload /bootsect.dos
# Change the colors.
title Change the colors
color light-green/brown blink-red/blue
Obviously you will have to edit it to make it work for you. I hope this gets you started. Come back with any questions.