In the specific case, the sampleImage() function was used in combination with other code to retrieve color information. However, no safeguards were put in place to specify the exact coordinates for the color sampling, so it would produce wrong results if the layer was moved.
Resolution or workaround:
If you are uncertain, always add layer space transforms such as .toComp() for such operations. Likewise, when dealing with colors, always make sure to use the correct syntax to conatin all color components in arrays.
its not that much helpfull, but what I've done: increased the RAM for after effects, and added an adjustment layer with motion blur on it, and it worked!
I strongly recommend that you re-examine your work flow. It isn't good practice to render in a different application in the background while trying to render in AE in the foreground.
Considering that AE can utilize up to 4GB per core, you're probably starving either AE or your 3D application of much-needed memory, and both are probably suffering.
Since we know nothing about your machine's processing and memory capabilities, nor the version of AE you run, that's about all I can tell you right now.
Oh, wait: until we know more, turn off multiprocessing in AE, and leave it off. That should help.
Thanks for the reply David. I seem to be having better luck actually with 10.01 - bit soon to tell if it's fixed as it was an intermittent error anyway.
For what it's worth, the background 3D rendering isn't that stressful - I've restricted Cinema to using 4 cores (out of 8) and the scenes aren't too RAM intensive. I'm working in SD/8-bit on this project too, so RAM isn't an issue (16Gb total).