[mattythebatty]

I've just installed Ubuntu using UNetbootin onto an external hard drive. My aim was to have Linux on the external hard drive and whenever that was plugged in and switched on it would boot from that, otherwise it would boot into Vista.

However, if the removable hard drive is not plugged in, then the GRUB bootloader fails to load and I can't even boot into Vista.

If it is plugged in then GRUB loads correctly and I can select which OS I wish to use.

My boot priority in the BIOS is currently for removable HDD then the internal Vista HDD.

Does anybody know how I can change this so it works as I intended?

Thanks.

[TerryNet]

I think you need to restore the Vista boot record on the hard drive (as if Ubuntu and the removable drive don't exist).

Maybe Grub can do this.

I understand that you can make the repair with a Vista installation DVD or a Windows Vista Recovery Disc.

[saikee]

If you have done it right then Grub should have been in the MBR of the external hdd. Therefore removing it will force the Bios to boot whatever is in the internal hdd's MBR which should be the one left untouched by Vista.

I believe you can still achieve it by

(1) While in Ubuntu check if the first boot disk is indeed the external hdd. You can compare the output of

sudo fdisk -l

and

sudo grub
geometry (hd0)
quit

If sda is indeed the external disk (hd0) then you can duplicate the MBR from internal disk to external disk by commands

sudo grub
root (hd0,0)
setup (hd0)
quit

assming you only have Ubuntu in (hd0) and the first partition has Grub inside which should be the normal case.

(2) You can restore the Vista's MBR by following the Task B7 of the Just booting tips in my signature. Both the lazy way asking the Vista or Win7 installation DVD to do it automatically or manually using the command "bootrec /fixmbr " in Command Prompt should work for you. The command "bootrec /fixboot" should be unnecessary in your case.

Thereafter your wish will be granted.

[mattythebatty]

Ah OK, I thought I might have to do something like this, thanks for the detailed advice. I'll try it tonight and post more thanks or questions depending on results :P