can not install ubiquity when installing Ubuntu 9.04

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Binary package hint: ubiquity

can not continue and finish installation of Ubuntu 9.04 because can not install ubiquity

ProblemType: Crash
Architecture: i386
DistroRelease: Ubuntu 9.04
ExecutablePath: /usr/lib/ubiquity/bin/ubiquity
InterpreterPath: /usr/bin/python2.6
MediaBuild: Ubuntu 9.04 "Jaunty Jackalope" - Release i386 (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 non accordée: '/proc/4954/environ'
PythonArgs: ['/usr/lib/ubiquity/bin/ubiquity', 'gtk_ui']
SourcePackage: ubiquity
Title: ubiquity crashed with InstallStepError in configure_ma()
Uname: Linux 2.6.28-11-generic i686
UserGroups: