Found a couple that are making gameplay hard.

The first is with the 'Blood on the Ice' quest. After I've finished speaking with Wuunferth in the prison, my quest log updates with 'Patrol the streets of the Stone Quarter at night'; as soon as that vanishes, it updates again saying that I've completed that and gives me the new log 'Catch the Murderer'. Calixto never again appears outside of Hjerim, and if I go there he automatically attacks me. However, I cannot kill him. He falls to the ground and a few moments later stands up again. This is incredibly frustrating because, not only can I not complete the quest, but I also own the house, and he always appears there. Oh, and if I attack him after he's gotten back up, I get a bounty on my character and the guards in town attack me.

The second glitch I've run in to, and the one that's going to prevent me from playing until it gets fixed, is that, during the first 'Companions' quest, while fighting the waves of Draugr, most of the environment started flashing a bright blue-white color. I left the dungeon, and the same thing is happening outside. I've tried loading a previous save, but it seems that the glitch is permanently locked in. In the blue areas I cannot see anything, and it sometimes affects npcs also.

I'm pretty aggravated so far. I paid for the Collector's Edition, and now I can't even play the game. It played fine up until around when I hit level 16, when the BotI glitch occurred, and now at 21 this second one has happened.