I just installed Ubuntu 7.10 onto a USB Hard Drive - which went smoothly - However now I cant boot the XP that is installed on the internal HD - if I unplug the USB Drive I get grub error 21 if I leave it in then I can get to the point where I select the OS - I choose XP and it goes through the xp start-up screen then flashes the blue screen of death and starts the boot process over again. HOW DO I FIX THIS?
I cant delete XP and start fresh (although I would like to) since it has my work files and programs.

Oh plus I need to have this fixed before 7 am tomorrow HAHA - but seriously - any help is greatly apreciated

A windows xp disk and in the repair mode at the command prompt type 'FIXMBR' without the prompts and hit enter.

Great Thanks

But will this problem arise again when I boot the external next time?

OK the FIXMBR was a no go with the external unpluged the XP recovery didnt even see the internal HD but with the external plugged in it sees it - so I did the mbr and rebooted first without the external HD and I got the same thing as before Grub Error 21 soI I plug the EXternal back in and I get the pick OS screen and XP does the same thing as before gets to its start-up screen and goes back to boot. However now I cant even boot the external HD, so I log onto the LiveCD to get the net.

You should be able to unplug the external hd, make sure your cd player is first boot in the bios boot order. Insert your windows cd and reboot the computer. Now the rest comes from memory so I may miss something but after the boot a screen will tell you there is a copy of windows and what do you want to do (installation) or (repair). Select the repair.

yes accept if I unplug the external then the recovery does not detect a hard drive?

I presume your windows is on an internal drive. If you ubuntu will boot from the usb drive in terminal give us the results of 'fdisk -l' without the quotes.

Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x8b21f3d3

Device Boot Start End Blocks Id System
/dev/sda1 * 1 9728 78140128+ 7 HPFS/NTFS

Disk /dev/sdb: 750.1 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x83f820fb

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 90835 729632106 83 Linux
/dev/sdb2 90836 91201 2939895 5 Extended
/dev/sdb5 90836 91201 2939863+ 82 Linux swap / Solaris

with the USB unpluged sda1 only shows up

If you have a good windows xp cd and your cd is first in the boot order you should be able to fix the mbr to boot windows xp. First lets figure out how you will be using this, do you plan on leaving the external drive installed full time or will you be disconnecting it. If you will be disconnecting it or adding more distros I will suggest setting up an indirect method of booting. If this is a permanent setup then we will fix what you should have now.

the external will not be pluged back in normally - I ran the recovery from my XP disk and did the fixmbr command but I could only access the internal hard drive with the usb pluged in with it unplugged the XP disk could not find any hard drive

Some reading on ubuntu and a usb hard drive that may help.

http://www.pendrivelinux.com/2008/04...drive-install/

You will not see another drive, XP does not like ubuntu's file system. You need to change the mbr and there are a couple of options. One is to change and boot from the XP boot loader in which I have never done. One other is to put a small partition (200 meg)on sda and install grub root there and then when you unplug your hd you will still be able to boot windows. Another is to get a grub super disk or your ubuntu disk and use it to boot ubuntu everytime you use it and when you unplug your external it still should boot XP. Before making any fast decisions checkout these options and if I can not help, I am sure some one can.

Yeah I had initially no problem with booting Ubuntu from the USB Drive it was when I tried to boot my XP from the internal that I had issues - I then preformed fixmbr from the XP CD recovery and now I cant boot to either HD I can only use the Live CD

When you installed Ubuntu you were given an option as to where to install Grub, the mbr or /boot directory. Did you install to the mbr? Of which drive? External where Ubuntu is, or the internal with windows? Your 'fdisk -l' output shows the 80GB drive as first drive Iw/xp)which is where your bootloader needs to be (Grub stage1 if you use Grub). The rest of the Grub bootloader files are in the /boot/grub directory of sdb1. If you have Ubuntu on the external disk and you don't expect to have it plugged in you won't be able to boot with Grub. Grub has several files as part of the bootloader and the only one in the mbr is stage1.

I selected to put them on the USB after following a trouble shooting guide - is there a way to but them on the internal?