Fix: Shivering Isles / Knights of the Nine DLC Not Working on Xbox 360

Common fixes for Oblivion DLC issues on Xbox 360:

1. Verify Installation: My Games & Apps → Oblivion → Manage Game → Ready to Install. Re-download if missing.
2. Clear Cache: Settings → System → Storage → [Device] → Clear System Cache (3x).
3. Delete & Reinstall DLC: Remove DLC from storage, re-download from Download History.
4. Disc Check: Clean disc (center-out). Try another Oblivion disc (GOTY edition includes DLC on disc).
5. Save File: Load a save before DLC trigger (receiving note/courier). Start new game to test.
6. Hard Reset: Hold power 10s → unplug 30s → restart.
7. Storage Space: Ensure >2 GB free on HDD/USB.

If persistent, contact Xbox Support—Marketplace purchase history may need refresh.