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drubru 05-15-2009 09:33 AM

Grub Error 21 with USB External Hard Drive and Other Problems
I have an HP tx2z with Vista Ultimate as my main OS. So a couple of days ago I decided to give Ubuntu v8.04 a try, but I didn't want to mess with my internall hdd, so I installed it on my USB 2.0 external hdd. Everything worked great (I thought), Ubuntu loaded up, it was fast, and I liked it. After I shut down the computer and unplugged the external hdd, I tried to boot to Vista and I got this message: "Grub step 1.5 loading" and "Grub error 21" (Not exact words, but you get the gist). BUT, I found out that if I do have my external hdd plugged in, it goes to a list of OS's that I can choose from, and Vista loads perfectly if that happens. But this is my portable laptop, I don't want to always have my external hdd plugged in just to boot into Vista. I did some research into this error and found that Grub can't read the 'selected disk' or something or other, so I'm guessing when I installed Ubuntu it put Grub on my internal hdd, not sure though. I don't mind having Grub on my internal hdd, but I would like to be able to run the computer in Vista without the stupid exteranl hdd plugged in. By the way, consider me a beginner with all this stuff, so if this problem requires rewriting code or whatever, you're going to have to hold my hand throughout the process. I would appreciate it if you guys responded quickly because my dad is coming in from out of the country and hasn't seen my new computer yet, he'd be royally pissed if he found out that I screwed up my computer already. Please help and thanks!

barunparichha 05-15-2009 09:42 AM

I will suggest for dual boot option in your internal hard disk. Because the grub might have been loaded in the internal hard disk (check /etc/grub.conf).

drubru 05-15-2009 09:55 AM

Ok, so if I just install say Ubuntu v9.04 on a partition of my internal hdd, this will all be fixed? That's the version I originally wanted to do but it would not recognize my external hdd so I went with the older one. Also, what is 'check /etc/grub.conf' ?

yancek 05-15-2009 03:20 PM

Grub has a number of files. The stage1 file is a small (512 bytes) file which can fit in the master boot record. When you install Grub, the default is to install stage1 to the first disk in boot priority so, unless you make that change yourself that's what happens. That's what did happen in your case based on the information you gave.

You can reinstall Ubuntu to the internal taking care that you do not overwrite your windows partition. You will need to select manual or expert install rather than taking defaults.

You could install Grub to the mbr of your external and then when you want to boot Ubuntu, select the external in your BIOS at boot.

You can use your vista installation CD to repair the vista mbr on the internal drive. To FIX VISTA MBR: Boot up from Vista Installation DVD and select Repair Your Computer option (its below Install Icon). Select Windows Vista -- Command Prompt.
Execute this at command prompt:
bootrec.exe /fixmbr
bootrec.exe /fixboot

If that looks problematic for you, you could download EasyBCD to edit the vista bootloader.

If you don't expect to have the external connected often, you would be better off restoring the vista bootloader on the internal drive. Check the neosmart technologies website (EasyBCD) or go to

drubru 05-15-2009 05:26 PM

yancek: Thank you so much, I will print this page off and try it I'll let you know if all goes well. I think I'm going to backup my computer first, though.

yancek 05-15-2009 07:15 PM


I think I'm going to backup my computer first, though.
Always a swell idea!!

drubru 05-16-2009 04:53 PM

yancek: Thank you so much for helping me out with my problem. I started this thread on three otherforums and no one really knew what I was talking about. I tried the OS disk route but it did not give me any sort of option besides reformatting my hard drive (no thanks), so I downloaded EasyBCD, and well, it was easy. After downloading it took literally 3 seconds to fix the problem, I rebooted, and now I'm really happy; and my dad didn't even have to find out. Thanks a bunch man.

yancek 05-16-2009 07:03 PM

Glad it works for you. I'm surprised you couldn't get help on other forums. This is a common problem for dual-booting and a simple solution.

As a father myself I'd suggest you tell your dad. You messed up, you took the inititative to learn, got it fixed and know how to do things most windows users will never know how to do. Also learned to research before you try something, right. Anyhow, your choice. Enjoy your new computer.

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