Yes, exactly. I have tried several ideas found in forums; pre-allocating RAM, decreasing it, decreasing the quality of the objects, turning off GI (using extra sunlight instead), rebooting first. Of course nothing else is on whilst rendering, and I have emptied the temp directory. I render at detail 0.5 and AA 0.5. I have 4GB of RAM and a brandnew and fast dual core CPU.
Just yesterday I tried one at 4500 x 2200, which crashed all the time, even when cropping in six parts. I tried 4200, which crashed as well (right at the start, the runtime message). When I got to 3900 it worked flawless. And very fast as well, the six parts were done in an hour or so.
I am still to try decreasing the number of threads to 2 or 0, which possible solution I found yesterday.
There seems to be some 'magic' threshold above which TGD doesn't even bother to load all masks and objects, hence my idea to render in smaller uncropped images and stitch them together.