a patch is now up for this game...see the bottom line about a fix to the vampire curehttp://news.teamxbox.com/xbox/13372/Shivering-Isles-Patch-is-Up-Fixes-Form-ID-Bug/
Update 1.2 Notes
10 new Xbox 360 Achievements for Shivering Isles <<<<<i dont know if this means 10 more achievements after the shivering isles extra ones,i will download it in a bit...................................EDIT:no it doesnt,i dont know why they have put this here
Improved LOD visual quality for landscape.
Optimizations to file loading system.
Taking items from dead owned creatures is no longer a crime.
Fixed issue where lock/unlocked states on doors would occasionally be stored incorrectly in a save game.
NPCs no longer pop into view after player cancels out from the Wait menu.
Fixed memory leak with sitting in a chair multiple times.
The reflection from the environment map in windows now displays properly.
Fixed an issue where player is still in combat even though the creature is no longer present.
Player can no longer fast travel when paralyzed.
Fixed infinite dialogue loop when arrested by guards who have high disposition to you.
Fixed issue where guards would not properly report crime if they were pickpocketed.
Summoned creatures properly fade away when they are created from a leveled list.
Fixed issue where stolen items would lose their stolen status if the player character was female.
Fixed crash that would occur with NPCs loading in with arrows.
Pickup sound effects no longer play during the loading screen.
If you attack a creature owned by you, crime is no longer reported.
Fixed issue with LOD not loading in properly when entering/exiting worldspaces.
Fixed infinite soul gems exploit by dropping and picking up stacked soul gems.
Fixed a crash with summoning a creature and immediately exiting the cell.
Fixed a crash with stealing an object, exiting and immediately re-entering an interior.
Fixed issue where an NPC would occasionally not perform the proper idle animation.
Fixed an occasional crash when a creature loses detection on the player.
Fixed an occasional crash with NPCs who were not loaded going into combat.
In Light the Dragonfires, fixed issue where improper journal would appear if you closed an Oblivion gate. In Till Death do They Part, fixed an issue where Melisande would not properly give you Cure Vampirism potion.