[Bryce Duncan]

I have experienced this using multiprocessor rendering in CS3–but when accessing source material on a network drive over ethernet. In my opinion, the multiple processes have trouble accessing the source material and then ‘time out.’ They render the footage as if it was missing and move on to the next frame. (This doesn’t seem to be an issue using one processor to render over the network.)

The error is also random because depending on how many processes you have running, the error could be generated by any one of them and that bad frame will be added to the finished render as soon as it is complete.