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. Please report this error at http://launchpad.net/aptdaemon/+filebug and retry. Traceback (most recent call last): File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 768, in simulate return self._simulate_helper(trans, status_path) File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 936, 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.
