The following packages have unmet dependencies:
virtualbox-qt: Depends: virtualbox (= 4.3.18-dfsg-1) but 4.3.18-dfsg-1 is to be installed
Depends: libgcc1 (>= 1:4.1.1) but 1:4.9.1-16ubuntu6 is to be installed
Depends: libqt4-network (>= 4:4.5.3) but 4:4.8.6+git49-gbc62005+dfsg-1ubuntu1 is to be installed
Depends: libqt4-opengl (>= 4:4.7.2) but 4:4.8.6+git49-gbc62005+dfsg-1ubuntu1 is to be installed
Depends: libqtcore4 (>= 4:4.8.0) but 4:4.8.6+git49-gbc62005+dfsg-1ubuntu1 is to be installed
Depends: libqtgui4 (>= 4:4.8.0) but 4:4.8.6+git49-gbc62005+dfsg-1ubuntu1 is to be installed
Depends: libstdc++6 (>= 4.6) but 4.9.1-16ubuntu6 is to be installed
sudo apt-get install -f
,sudo apt-get update
,sudo apt-get dist-upgrade
, then try again?