The following packages have unmet dependencies:
 virtualbox-4.0 : Depends: libpython2.6 (>= 2.6) but it is not installable
                  Recommends: libsdl-ttf2.0-0 but it is not going to be installe                                                                                                                                                             d
                  Recommends: libhal1 (>= 0.5) but it is not going to be install                                                                                                                                                             ed
                  Recommends: pdf-viewer
                  Recommends: python-central but it is not going to be installed
E: Unable to correct problems, you have held broken packages.