Cinnamon 2.0 has been only launched for a few days now and a lot of people have installed it on their Ubuntu 13.10 (Saucy Salamander) machines. That might have been a terrible mistake.
Users have started complaining about the fact that Cinnamon 2.0 has somehow corrupted their Unity desktop environment. We ran a couple of tests on three different machines and all of them are now refusing to boot into the normal desktop of the distribution, Unity.