I use Debian Jessie, and I am the type who do this command frequently:
sudo apt-get update && sudo apt-get dist-upgrade
Now I am suffering from the consequences. The desktop is completely broken. I googled around, and there was nothing. So I thought something in my laptop is broken at first.
Well, if you are a long enough linux user, this kind of stuff is kind of normal. It always happens once in a blue moon. It happened once when I was upgrading Fedora. It happened once when Debian removed ati driver. This stuff is normal, it’s also Debian Testing anyway. One just need to keep calm and fix the problem.