The last time I tried making a model, probably at least a year ago, I was using Poser 5.0 and Blender 2.34 (I think), and I don't know what it was that I did specifically, but I had no problems exporting OBJ from Blender and loading them into Poser.

I've since upgraded to Poser 7.0 and Blender 2.44.  The first model I have tried to make crashes Poser (without error message) when I tried to load the OBJ file into Poser.

Reading around and trying to find help on the issue, I have gathered that the new Python script included with Blender for exporting OBJ doesn't necessarily produce OBJ files compatible with Poser, and that either the options need to be tweaked or alternate python scripts use.  So far, however, I haven't been able to find exactly what options anyone has used when exporting from Blender for use into Poser, or what other scripts they might be using.

Any advice for me?

To determine if it is Blender's export function and not a flaw with your model, Import a Poser model (the .obj file should be in a 'geometry' folder).  Then Export it with a new name and try importing into Poser.

Have used 2.44 myself and eventually went back to 2.43 as most of the import/export scripts seemed to be on the fritz. As for options, the default selections work just fine, the only option I really use is to export a selected object or the whole model. The only time I have found that a mesh doesn't import properly for me is when the mesh has been a bit dodgy. Things like double edges, faces etc. Some people say that installing Python has helped others say different. For me, going back to 2.43 was a lot easier than sorting out the problems with .44. I can wait until the next release as I've hardly scratched the surface of many of its features.

I've got Python 2.5 on my system so that could be the answer since I've had no problems with formats I've tried.  You may want to consider installing it also since the next version of Blender will probably need it to.

I fairly certain the default OBJ export options need to be changed for Poser.

I'd suggest that you don't export Normals, and use "Object Groups" instead of "Objects".