Have you checked this thread? http://bit.ly/GYv0b2
It's about the mods to make the game run better especially on modern hardware and Windows 7. I never played PST before and I just ran through them all on recommended settings and I have no camera issues.
If it's not game specific then it could be a driver issue. I remember reinstalling or updating the software for my Razer mouse backthen when I had that issue and it disappeared (for a while).