I've experienced this with Poser Pro 2012 with and without SR2 myself, it seems to be related to the external morph targets, as the out of memory message often comes with another message stating the PDM file could not be loaded.

I'm yet to file the bug, I'll try to point out the exact conditions under which the problem apears before doing so.

I love external morph targets, it makes the scene load and save SO much faster, but it can cause so many problems I'm starting to think it's not really worth using.