External HD install: No OS found error

[Husse]

Well that's about what I would expect to happen if you can't change boot order in BIOS, which is not to be expected in a laptop
How would the boot order be decided....
But there is a solution - luckily
Download and burn Supergrub (google for it) to a CD (its about 4 MB so that download is no problem)
Then use supergrub to install grub.
Alternatively you could make manual changes to menu.lst in the existing grub.
With XP in the first partition as you have you should add

Code: Select all

title		Microsoft Windows XP Professional
root		(hd0,0)
savedefault
makeactive
chainloader	+1

Then follow this wiki
http://www.linuxmint.com/wiki/index.php ... _your_grub
Perhaps as easy to do as Supergrub and you learn some
There is a but. If this had been two different Linux, perhaps the one on the internal drive would complain if the USB drive was not connected but would continue booting
XP being less sophisticated and called upon in a different way from grub would not even notice it

[Husse]

Now that's surprising....
You set USB to boot first and yet it does not? Semi hardware error (wont go into the details of booting )
Grub is already on your USB drive
I need to explain a bit
You will find a folder /boot that contains grub and in dual boot with XP that's on the Linux partition
I think you know that
When we talk about putting Grub on this or that disk (like you can do when you install from the "Advanced" button in the las dialog box) it's grub stage one which is a miniscule (only a few hundred bytes) program.
You should have that on the internal disk, and then of course you need something to start windows from the later stages of grub. I don't think you have that now as you installed with the XP disk disconnected, so you can use my suggestion to fix that little problem
So booting will always start with the internal drive, but you are given the choice to decide where it will continue

[Husse]

Did you do it exactly as stated in the wiki (with necessary changes for your needs of course)?
Have you checked the menu.lst?
Must ask this because this is crazy
When I write this a thought hit me (hard )
This is not used these days, but do you have some Boot sector protection/antivirus?
That blocks writing to MBR
Check BIOS and disable it if it is enabled and repeat the repair grub stages.
You should not have to add XP in menu.lst again
If you do not have that enabled it is either a hidden Boot sector protection or a virus in MBR (or very unlikely some special boot sector that can't be handled in normal ways)
All this is said presuming it is not an Apple laptop, because that changes the entire scenario