ubiquity crashed with ValueError in command()

[Mario S.]

Binary package hint: ubiquity

installation crashed after downloading the translation packages (german) from the LiveCD install.

ProblemType: Crash
Architecture: amd64
DistroRelease: Ubuntu 9.04
ExecutablePath: /usr/lib/ubiquity/bin/ubiquity
InterpreterPath: /usr/bin/python2.6
MediaBuild: Ubuntu 9.04 "Jaunty Jackalope" - Release amd64 (20090420.1)
Package: ubiquity 1.12.12
ProcAttrCurrent: unconfined
ProcCmdline: /usr/bin/python /usr/lib/ubiquity/bin/ubiquity gtk_ui
ProcEnviron: Error: [Errno 13] Permission denied: '/proc/6221/environ'
PythonArgs: ['/usr/lib/ubiquity/bin/ubiquity', 'gtk_ui']
SourcePackage: ubiquity
Title: ubiquity crashed with ValueError in command()
Uname: Linux 2.6.28-11-generic x86_64
UserGroups: