bigal,
If I understand correctly, you are booting your running system from an external USB drive.
...
That's the reason you are getting the "unable to copy files to new root" error message.
Hello,
I wonder why I do not get that error when I install from a LiveCD booted off a flashdrive,
where the target is another flash drive.
I am getting that error on one flash drive but I think it is due to the drive being bad and
unmountable.
regards,
patrick013