This Shivering Isles patch (English language version) fixes various issues related to form IDs (objects in the game).
Update 1.2.0416 Notes
Bug Fixes
Fixed a crash caused by bad form IDs
Fixes an issue where the game would try to use a form IDs that was either restricted or not available yet.
Fixed an issue where form IDs were not being marked as free properly, causing objects to disappear in game.