I'm on an old desktop now and while I find I can still use Poser (Yayyyyyyy for me!), I find that I get that error a whole lot. First I get the message about Windows allocating more memory, and then another window telling me that  I've run out of memory and the render failed, or something along those lines.  The only way to exit Poser 6 for me at that point is to CTRL ALT DEL and then reboot.

Some work arounds that I've been doing:

1.  Making sure the shadow maps on my lights do not exceed 256;
2.  Resizing the texture files (using bicubic resample so it doesn't blur) for things I'm using in my scene to 1024 on the long side;
3.  Hiding body parts under the clothing that aren't going to be visible in the image;
4.  Hiding all but one item and then rendering that item. Then hiding it and unhiding something else and rendering that. For figures I often have to hide the upper or lower part of the body, and render the unhidden part, then hide that part and unhide the other half and render that.

Then I piece it all together in my graphic program. It works pretty well because I have the same lights for all renders so things look like they were done together.

As for raytracing?  Sadly I find I can't do much of that and have to do most of my shiny metal looks in post work. 

Resizing your textures can help a great deal.  But if you resize, make sure you pick "bicubic resample" instead of "smart size" so you don't lose detail.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi