I've managed to break apt-get, I think it had something to do with competing versions of libqt between supercollider and Skype. When I run apt-get -f install I get:

Reading package lists... Done

Building dependency tree       

Reading state information... Done

Correcting dependencies... Done

The following packages were automatically installed and are no longer required:

  libxml++2.6-2 libffado2 libconfig++8 libssl1.0.0:i386

Use 'apt-get autoremove' to remove them.

The following extra packages will be installed:

  libqt4-declarative:i386 libqt4-sql-mysql libqt4-sql-mysql:i386 libqt4-test qdbus

Suggested packages:

  libqt4-declarative-folderlistmodel:i386 libqt4-declarative-gestures:i386 libqt4-declarative-particles:i386 libqt4-declarative-shaders:i386 qt4-qmlviewer:i386

  libqt4-dev libqt4-dev:i386

The following packages will be upgraded:

  libqt4-declarative:i386 libqt4-sql-mysql libqt4-sql-mysql:i386 libqt4-test qdbus

5 upgraded, 0 newly installed, 0 to remove and 449 not upgraded.

14 not fully installed or removed.

Need to get 0 B/1,236 kB of archives.

After this operation, 0 B of additional disk space will be used.

Do you want to continue [Y/n]? y

(Reading database ... 183437 files and directories currently installed.)

Preparing to replace libqt4-sql-mysql 4:4.8.1-0ubuntu4.1 (using .../libqt4-sql-mysql_4%3a4.8.1-0ubuntu4.2_amd64.deb) ...

Unpacking replacement libqt4-sql-mysql ...

dpkg: error processing libqt4-sql-mysql:i386 (--configure):

 libqt4-sql-mysql:i386 4:4.8.1-0ubuntu4.1 cannot be configured because libqt4-sql-mysql:amd64 is in a different version (4:4.8.1-0ubuntu4.2)

dpkg: error processing libqt4-sql-mysql (--configure):

 libqt4-sql-mysql:amd64 4:4.8.1-0ubuntu4.2 cannot be configured because libqt4-sql-mysql:i386 is in a different version (4:4.8.1-0ubuntu4.1)

Errors were encountered while processing:

 libqt4-sql-mysql:i386

 libqt4-sql-mysql

E: Sub-process /usr/bin/dpkg returned an error code (1)

I read that I could fix this by installing aptitude and removing and reinstalling broken packages, but I can't install it using dpkg.