I had ubuntu 10.04 installed on an external usb drive (partitioned: ext4, swap and ntfs), that worked just fine and grub booted as it should (only when the usb drive was plugged in).
Then I got a bigger drive (2TB, WD) and tried to install ubuntu 12.04, as I did before.
It appeared to install without a hitch.
But GRUB wouldn't boot. I just get a very long initial sony screen, then a very long blank screen with blinking cursor, then "read error".
I read that sometimes boot gets put too far into the drive on bigger drives (although only 300GB of that was in ubuntu formats), so I tried adding extra partitions /boot and then /boot and /root. Didn't make any difference.
So I tried Boot Repair (and I didn't want GRUB on my main hard drive, so I did use the advanced settings to change that) and got the following URL which I sent to the email provided, but they also suggested posting it on a forum, so here it is:
It's a bit of a mess since there are probably more partitions than needed, but I tried first without. There is also a record on this URL about my other external HDD...that is sdb, which I don't have plugged in at the time of the boot-repair...not sure if that is confusing.
So, I've reinstalled about 4 times and repartitioned....both during install and pre-done with gparted. since I have no way to get into ubuntu, i'm really not sure what to do.