Sorry if this is a silly question, but I'm a bit puzzled at getting a memory error during rendering with c7 pro.

I had stonemasons Urban Futures and one figure (shukky's bonebot) loaded with a sunlight. 60% into the render I recieved a memory allocation error and that was that. I'm running Xp home on a dual core amd althon 6000 x64 with 4 gb memory. Granted that I'm only actually using half that should I still get a memory error on a scene I can easily render in Daz 3 advanced with ibl lighting? I've had some scenes clunk away for days (in Daz 3 adv) with no problem using atmosphere, ibl plus shader lights but why tank out with 1 figure, and one set prop, with no fog, atmosphere or anything other than a sunlight?