I have enjoyed this game throughly to this point, it seems that once I kill Adamus Phillida and attempt to save, fast travel, enter Cheydinhal or anything to complete the quest my X-Box locks andI have a black screen, I've tried walking to Oceeva, riding, fast travel just about anything you can think of to no avail. once I make the kill the game hangs/stops.

Clear your game cache, and see if that doesn't help. (press and hold the A button while turning your xbox on.)