<type 'exceptions.SystemError'>: E:I wasn't able to locate file for the ttf-mscorefonts-installer package. This might mean you need to manually fix this package.

[Cliffm]

Binary package hint: aptdaemon

Want to install virtual Box
When attempting to run Synaptic Package Manager the following occurred
           'an error occured'
    The following details are provided:
    E: dpkg was interrupted,you must manually run 'sudo dpkg-configure-a'
      to correct the problem.
    E:_cache->open() failed, please report.

Opened terminal and ran the above as requested.
     sudo dpkg-configure-a: command not found
Re-ran: ~$ sudo dpkg configure-a
dpkg: error: need an action option

Type dpkg --help for help about installing and deinstalling packages [*];
Use `dselect' or `aptitude' for user-friendly package management;
Type dpkg -Dhelp for a list of dpkg debug flag values;
Type dpkg --force-help for a list of forcing options;
Type dpkg-deb --help for help about manipulating *.deb files;

Options marked [*] produce a lot of output - pipe it through `less' or `more' !

Retried using Ubuntu software center
    Same result as above.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: aptdaemon 0.41+bzr645-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
Annotation: Applying software changes failed
Architecture: amd64
Date: Sat Apr 16 17:54:07 2011
DesktopFile: /usr/share/aptdaemon/aptdaemon.desktop
ExecutablePath: /usr/sbin/aptd
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Beta amd64 (20110413.1)
PackageArchitecture: all
SourcePackage: aptdaemon
Title: <type 'exceptions.SystemError'>: E:I wasn't able to locate file for the ttf-mscorefonts-installer package. This might mean you need to manually fix this package.
TransactionDepends: [[], [], [], [], [], [], []]
TransactionErrorCode: error-unknown
TransactionKwargs: {}
TransactionLocale: en_US.UTF8
TransactionOutput:

TransactionPackages: [[dbus.String(u'virtualbox-ose-qt')], [], [], [], [], []]
TransactionRole: role-commit-packages
UpgradeStatus: No upgrade log present (probably fresh install)