The famous "memory error" in Poser doesn't actually mean there is a problem with memory at all. It is the general message indicating something is wrong. Quite often it means some reference is incorrect (a texture map was removed or moved, or any other element referenced isn't where it is expected to be). Several tools are available to check for (and fix) these kind of reference problems. Apply the tool on anything you consider suspect (including scenes). Whenever you encounter the problem be sure to stop Poser asap and restart as Poser can become unstable.

The problem has been with Poser since the first version and has become rarer with later versions (and patches) but may still happen even with the latest versions.