Issue with the game on the 360. Help.

Just FYI, spoilers for the Dark Brotherhood quest line follow. So I return to the Sanctuary after [Dark Brotherhood Spoiler](/killing the Emperor's double and escaping Solitude and find the rest of the Brotherhood dead, except for Nazir.) However, after I save him and run to the Nightmother's coffin to get in, she says her scripted lines and the screen fades to black after crashing and splashing noises are heard. My problem is that every time I do this, my screen just remains black, like forever. I can hit the middle button on the controller to bring up the Xbox menu, but I only hear the button as the menu doesn't appear through the black screen. After this, it sounds like my console freezes or something. Eventually I just loaded my game and turned around to walk out of the Sanctuary and do some other quests, but it would really grind my gears if I couldn't complete this badass quest.

Unrelated, but another weird thing that happened was that somewhere between plays I lost the ability to summon Arniel's shade. Odd.