Yes, that's it. Thanks, anyway. I've sussed it after a call to Smith Micro. My Nvidia GT220 doesn't seem to fully support the flavour of OpenGL that Smith Micro have programmed for. Updating the drivers didn't make any difference. Switching to SreeD did.

Maybe the Gurus here can elucidate- would an Nvidia Quadro video card make any difference to OpenGL support with Poser?