I’ve just tried installing Ubuntu but when it restert for the first time, GRUB returns an Error 21. I know this means that it can’t find the grub.conf file, but I don’t know how to fix this. I used Windows XP’s Recovery Console to get back into XP, but I can’t access the GRUB files.

1. Boot your computer up with Ubuntu CD

2. Open a terminal window or switch to a tty.

3. Go SuperUser (that is, type “sudo -s”). Enter root passwords as necessary.

4. Type “grub”

5. Type “find /boot/grub/stage1″. You’ll get a response like “(hd0,1)”.

Use whatever your computer spits out for the following lines.

6. Type “root (hd0,1)”, or whatever your hard disk + boot partition numbers are for Ubuntu.

7. Type “setup (hd0)”, to install GRUB to MBR, or “setup (hd0,1)” or whatever your hard disk + partition nr is, to install GRUB to a partition.

8. Quit grub by typing “quit”.

9. Reboot and remove the bootable CD.

Note:- In the above procedure hd0,1 is an example it might be different in your case.