One external USB disk, partitioned as:
1. NTFS: General data
2. Linux Swap
3. EXT3: Ubuntu installed

One internal hard disk (NTFS)
1. NTFS: Windows XP installed.

My problem is thus:
When the computer starts it boots GRUB from the internal disk, unfortunately GRUB looks for it's config files on my external USB Disk and refuses to start without this disk displaying 'Error 21'.

This means I can't even boot Windows without having my second disk always attached.

Is it possible to change the location of the GRUB config files to my internal, NTFS Windows disk?

Install GRUB for Windows/DOS; https://sourceforge.net/projects/grub4dos

Edit: grub4dos corrupted my boot sector and gave me a screen with GRUB GRUB GRUB GRUB, etc on it. I've managed to reinstall the original grub but I'm no further in solving my original problem

I have never tried this, but how about making a small ext3 partition on the internal drive?

Don't forget that grub must be installed based on where the config file is. It gets "hard-coded" to point to that location.

When I have 2 disks, I prefer putting all the OSes on one, and the data partitions on the other. This may be too big a change to deal with your issue.

I used grub4dos early in its public life - seemed to work fine.
Options:
- create a boot partition on the internal disk as mentioned (gparted should handle this).
- Use the 'doze loader. Instal grub to a partition on the external, and copy the boot sector record to your 'doze system partition. Plenty of howtos here on LQ and on the wider net.

... or just use another boot loader. GAG will do the job, it installs to the first sectors of your HDD, no boot partition needed, no need to worry about it's files.

Yep, keep forgetting that handy little attribute.

i installed ubantu on a flash drive which then installed grub when the grub menu came up it had linux and xp i highlighed over linux and pressed enter the all this text came up and at the bottom it said kernel error so i waited 10 mins and nothing happed so i restarted an to booted up xp then i wiped the flash disk and then restarted the computer and now says grub error 21 i would really would be great if someone could fix this for me because i have inprortant data in the computer thanks Amph Technology

Boot your XP CD ad hit <r> to get into Recovery Console when told.
Run fixmbr
Reboot.