ubiquity crashed with ValueError in raw_decode(): No JSON object could be decoded

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Crash occurred when launching the Ubuntu installer while booting off a USB drive

ProblemType: Crash
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 Nov 14 16:59:53 2011
ExecutablePath: /usr/lib/ubiquity/bin/ubiquity
InterpreterPath: /usr/bin/python2.7
LiveMediaBuild: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
ProcCmdline: /usr/bin/python /usr/lib/ubiquity/bin/ubiquity --only
ProcEnviron: Error: [Errno 13] Permission denied: '/proc/3196/environ'
PythonArgs: ['/usr/lib/ubiquity/bin/ubiquity', '--only']
SourcePackage: ubiquity
Title: ubiquity crashed with ValueError in raw_decode(): No JSON object could be decoded
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #887879, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.