I'm looking into it. I'll see what I can do about the problem. But if you're doing post work (exposure/brightness) that could be done in TG2 anyway, might as well do it there as the results should be better.
Btw, one thing I notice in your file, a 4000MB cache allocation! You're probably getting nowhere near that since the scene is fairly simple, but if it did try to use all that, you'd crash because TG2 is 32 bit and 4000MB puts it beyond its usable memory (given other memory-using elements like image buffers, etc.). There's really little need to have more than 200MB *per thread* in most cases. So for you, with 4 threads, an 800MB cache ought to be fine. Even 400MB would suffice, but 800 might be a bit faster.
I'll let you know how my tests work out.
- Oshyan