Hello. I installed Oblivion and used the Oblivion patch 1.2.0416. I have noticed items I drop on the ground disappear. I thought this was a bug related to Shivering Isles which I haven't installed, and was addressed with the 1.2.0416 patch. Is there a reason why this is happening?

Also, I would like to play Shivering Isles eventually. Do I need to reinstall Oblivion (since I used the 1.2.0416 patch) before installing Shivering Isles?

Many thanks.

PC UK, European, Australia version
Windows XP, service pack 3.