If you've been spending long hours exploring the new realms opened in The Elder Scrolls IV: The Shivering Isles on your PC, you may be affected by an in-game bug. Some players of the PC version have reported that, upon reaching 50 hours of play time after installing the expansion, a script error occurs. This error prevents new items from spawning. Reports indicate that the glitch occurs after 50 hours of overall play time, whether or not that time was spent in the new areas opened by the expansion.
Bethesda has already issued a beta patch on its Elder Scrolls website. The patch notes indicate that it "fixed an issue where form IDs were not being marked as free properly, causing objects to disappear in game." Bethesda also indicated that as this is a beta patch, it may cause undesired results. Saved games should be backed up before installing the beta patch.