My attempt to upgrade to 12.04 failed, so I burnt a 12.04 CD, and asked to do a full install, getting rid of all previous OS (I had Windows as well as 11.10). All seemed well until the very end when it said it had failed to install GRUB. I tried selecting different partitions to try in, with the same result. I can proceed without installing GRUB, but then it tells me I have to manually install the boot loader. A long Google session has failed to come up with any instructions to do this that I can understand. Help.
Here's what I'd do:
Boot the machine using a Live CD.
Open a terminal.
Find out the name of the internal disk by using fdisk to look up the device's size.
sudo fdisk -l
Install GRUB boot loader onto the proper disk (the example below assumes it is
sudo grub-install --recheck --no-floppy --root-directory=/ /dev/sda