I have a cheeky little fix for the grub Error 21 problem. I was trying to install Ubuntu on my Dell Inspiron 3500 as I herd it had better wireless support. When I ran into the same problem. Since Ubuntu's Grub is a bit rubbish use another version instead!
The fix is, boot your laptop with a recuse cd , I this case I used one I had for fedora core 5 (I did try knoppix but that wouldn't work). When you boot up let it mount the drive, once your at prompt, type grub , then setup as normal. This takes account that you have /boot.. setup and you grub.conf/menu.1st setup. (go here to find that out - https://help.ubuntu.com/community/Installation/FromKnoppix) ie -> grub> root (hd0,0) -> or what every disk you want to install grub on. then grub> setup (hd0) then "quit" grub and reboot. I did say it was a cheeky fix, but it works! Job done! -- Grub - Error 21 returned https://launchpad.net/bugs/8978 -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
