I was hoping someone would be able to assist me with my issue. I recently bought and downloaded the steam version of Oblivion and it quickly became apparent my computer was not running it properly. The problem is that when encountering certain enemies (zombies, humans, even deer) my game becomes a slideshow. My system should be more than capable of handling the game on high settings, especially considering I haven't had any issues with Fallout 3 or New Vegas.

Windows XP with SP3
3.6 GHz Intel Core i5
4 GB 1333 MHz DDR3 ram
ATI Radeon HD 5670 512 MB

Any insight on what could be causing the stutter would be hugely appreciated.