Yes, that sounds like it could be low memory. Also, be sure to check that you have the patch to 2.1, because that will be a lot more stable than v.2 and might solve the import problem. Or, with Poser figures, be sure to export each separate model (figure, shirt, pants, shoes, hair) individually, then import them one at a time. If you've UNchecked the "resize and center" option (in Options/Preferences), each item will import right into position relative to each other (the hair will be on the head, for instance) but the file sizes of the DXF will be much lower and more likely to import okay.