I have this problem too. I've searched on the internet for solutions with no success. However, I did find out that integrated graphics cards could be the reason that Magicka crashes as it does. I'm able to play all the Challenges and even the vampire DLC (The Other Side of the Coin), and also the first chapter of Dungeons and Daemons. I cannot play the other chapters of Dungeons and Daemons, nor the entire Dungeons and Gargolyes DLC, nor the The Stars Are Left DLC. And whenever I attempt to play them, the game exits as if what I pressed was the "quit" button. I play Magicka through Steam, by the way, although I would like to separate Magicka from Steam because I think having Steam opened might contribute to this problem.