There seems to be a programming error in aptdaemon, the software that allows you to install/remove software and to perform other package management related tasks.

[shiva]

File "/usr/lib/python2.7/dist-packages/aptdaemon/worker.py", line 968, in simulate
    trans.unauthenticated = self._simulate_helper(trans)
  File "/usr/lib/python2.7/dist-packages/aptdaemon/worker.py", line 1092, in _simulate_helper
    return depends, self._cache.required_download, \
  File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 235, in required_download
    pm.get_archives(fetcher, self._list, self._records)
SystemError: E:I wasn't able to locate a file for the ttf-mscorefonts-installer package. This might mean you need to manually fix this package.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: software-center 5.0.1.4
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic i686
NonfreeKernelModules: wl
ApportVersion: 1.23-0ubuntu3
Architecture: i386
Date: Sat Dec 24 09:54:07 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: software-center
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 659438, so it 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. Feel free to continue to report any other bugs you may find.