Installer crashed on trying to install to external disk

[Steven Pemberton]

Installing onto an external disk (which will eventually replace the internal one).

Couldn't write the boot partition (sorry, I failed to write down the exact message).

Warns me that I may not be able to boot my machine. Haven't yet checked.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.16
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu5
Architecture: amd64
CasperVersion: 1.315
Date: Thu May 17 21:38:00 2012
InstallCmdLine: noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 LANGUAGE=en_US.UTF-8
 TERM=linux
 PATH=(custom, no user)
 LANG=en_US.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu Foundations Team Bug Bot (crichton)]

Exception during installation:
May 17 19:37:55 ubuntu plugininstall.py: Traceback (most recent call last):
May 17 19:37:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1735, in <module>
May 17 19:37:55 ubuntu plugininstall.py: install.run()
May 17 19:37:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 55, in wrapper
May 17 19:37:55 ubuntu plugininstall.py: func(self)
May 17 19:37:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 204, in run
May 17 19:37:55 ubuntu plugininstall.py: self.configure_bootloader()
May 17 19:37:55 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1013, in configure_bootloader
May 17 19:37:55 ubuntu plugininstall.py: "GrubInstaller failed with code %d" % ret)
May 17 19:37:55 ubuntu plugininstall.py: InstallStepError: GrubInstaller failed with code 1
May 17 19:37:55 ubuntu plugininstall.py: