ubiquity-dm crashed with ValueError in command(): invalid literal for int() with base 10: ''

Binary package hint: ubiquity

Crash happened while installing Natty Alpha 3 downloaded 22.30 3rd March 2011.
Download updates while installing switched on. Install MP3 codecs switched on.

Installed own partitioning arrangement. SDA1 = ext4 primary partition containing Ubuntu 10.10 desktop. SDA6 = Extended partition containing /home. SDA7 = extended partition previously containing Mint KDE, reformatted to ext4 to be the container for Natty Alpha3 and SWAP as normal. SDB1 = Windows Vista 32bit on seperate hard drive.

Installation crashed approximately 3/4 along progress bar after all the options had been selected and confirmed and after updated had been downloaded and files were being copied and installed.

Installer crashed out back to live CD allowing me to file this bug report.

Sorry - unable to access /var/log to attache log files - could not mount that partition.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: ubiquity 2.5.22 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 2.6.38-5.32-generic 2.6.38-rc6
Uname: Linux 2.6.38-5-generic i686
Architecture: i386
Date: Fri Mar 4 09:30:25 2011
ExecutablePath: /usr/bin/ubiquity-dm
InterpreterPath: /usr/bin/python2.7
LiveMediaBuild: Ubuntu 11.04 "Natty Narwhal" - Alpha i386 (20110302)
ProcCmdline: /usr/bin/python /usr/bin/ubiquity-dm vt7 :0 hostname /usr/bin/ubiquity --greeter --only
ProcEnviron:
 LANGUAGE=
 PATH=(custom, no user)
 LANG=en_US.UTF-8
PythonArgs: ['/usr/bin/ubiquity-dm', 'vt7', ':0', 'hostname', '/usr/bin/ubiquity', '--greeter', '--only']
SourcePackage: ubiquity
Title: ubiquity-dm crashed with ValueError in command(): invalid literal for int() with base 10: ''
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: