The Shivering Isles expansion pack for The Elder Scrolls IV: Oblivion adds a new land to explore--the Realm of Madness--along with 30 hours of new gameplay, new creatures, dungeons, and quests. For some users, it also includes a bug that could break the game.
Bethesda Softworks has confirmed that a major glitch in The Elder Scrolls IV: The Shivering Isles exists and that it is working to fix the problem. The bug apparently starts affecting the game as soon as the expansion pack is installed for the PC version of Shivering Isles. The problem arises because the game generates a huge number of identification numbers internally for objects, and once the allotted space for those numbers becomes exhausted, newly created objects will disappear from the gameworld and the game could simply crash.
Depending on the number of frames per second generated on a user's PC, the game will be "rendered unplayable" from between 50 to 120 hours of gameplay, according to reports in the official forums and the game's Wiki. It appears that the more frames per second the game runs at, the faster that space of identification numbers fills up.
"We have verified this problem can happen on the PC and are still looking into whether it is possible on 360, since we don't have any reported cases of it happening on that platform, nor have we been able to recreate it on 360 ourselves," a Bethesda spokesperson told GameSpot. "We're testing a fix for it right now and hope to have it out as soon as possible."
[UPDATE] Bethesda has released a beta patch for The Shivering Isles that addresses the form IDs problem. The file, which bumps the expansion up to version 1.2.0410, is available at The Elder Scrolls Web site.
"We wanted to get something out for PC users as quickly as possible to try and address the problem with this beta patch," a Bethesda rep told GameSpot. "We are trying to be as responsive as possible while making sure that any updates we release don't cause additional problems."
The rep also said that there have been no reported cases of a similar problem affecting the Xbox 360 version.