grub bootloader fails to start and crashes Oneirec Ocelot installer

[Midnight Matt]

I've tried several times now to install Ubuntu 11.10 on an external hard drive connected to a Dell Inspiron 8600 laptop and each time the installation failed and the installer crashed. The contents of both the /var/log/syslog and the /var/log/partman files are attached as requested.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: ubiquity 2.8.7
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic i686
ApportVersion: 1.23-0ubuntu3
Architecture: i386
CasperVersion: 1.287
Date: Mon Apr 2 22:42:23 2012
LiveMediaBuild: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu Foundations Team Bug Bot (crichton)]

Exception during installation:
Apr 2 22:41:56 ubuntu plugininstall.py: Traceback (most recent call last):
Apr 2 22:41:56 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1641, in <module>
Apr 2 22:41:56 ubuntu plugininstall.py: install.run()
Apr 2 22:41:56 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 55, in wrapper
Apr 2 22:41:56 ubuntu plugininstall.py: func(self)
Apr 2 22:41:56 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 210, in run
Apr 2 22:41:56 ubuntu plugininstall.py: self.remove_extras()
Apr 2 22:41:56 ubuntu plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1404, in remove_extras
Apr 2 22:41:56 ubuntu plugininstall.py: if self.db.get('apt-setup/restricted') == 'false':
Apr 2 22:41:56 ubuntu plugininstall.py: File "/usr/lib/python2.7/dist-packages/debconf.py", line 60, in <lambda>
Apr 2 22:41:56 ubuntu plugininstall.py: lambda *args, **kw: self.command(command, *args, **kw))
Apr 2 22:41:56 ubuntu plugininstall.py: File "/usr/lib/python2.7/dist-packages/debconf.py", line 81, in command
Apr 2 22:41:56 ubuntu plugininstall.py: status = int(status)
Apr 2 22:41:56 ubuntu plugininstall.py: ValueError: invalid literal for int() with base 10: ''
Apr 2 22:41:56 ubuntu plugininstall.py: