Using Karmic Repositories
As a final attempt I decided to use the Karmic repositories. I added them to apt:
sudo gedit /etc/apt/sources.listI then copied my current Ubuntu repository, "deb http://gb.archive.ubuntu.com/ubuntu/ natty universe", pasted it on a new line and changed "natty" to "karmic".
Opening up Synaptic Package Manager I searched for the "mediatomb" package. With it highlighted, I used the "Package" menu at the top of the window to firstly "Force Version" to the Karmic package and then "Lock" it. I did this for the following packages: