Can you post the exact error? Does it mention what packages are causing issues, or does it just ask you to run "apt-get -f install"?
I had a very similar problem - there was an updated version of hildon-initscripts in the tools repo that bust the mp- package when I did a dist-upgrade. I did an apt-cache policy hildon-initscripts to see the versions available, then rolled back using apt-get install hildon-initscripts=version.number I think. After that I was able to put back the mp- package (and simultaneously install pr1.2) with a normal apt-get install.