Comment 2 for bug 717519

Same happened to me, so I exited the terminal. Now when I try to install via Ubuntu Software Center I get the following error message:

Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 779, in simulate
    return self._simulate_helper(trans, status_path)
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 958, in _simulate_helper
    return depends, status, self._cache.required_download, \
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 218, in required_download
    pm.get_archives(fetcher, self._list, self._records)
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.

Help!
Thanks