I have been running into some problems with the driver based frame change event system. It seems to be problematic when rendering. I have been looking into another way to simulate a frame change event and have come up with a threaded sampling concept that seems to solve this rendering problem.
Feel free to download the BLEND file. Press play to see CameraPlus threaded version in action.
I have only tested this system on Windows XP64 using Blender 2.5 32bit and 64bit builds. So any feedback as to the reliabilty of this concept on other OS’ would be great.