FINALLY SOLVED !

Oddly, ATI released a new Catalyst driver set earlier this month, see their site referenced below.  I had updated previously to the 10.5 set and still had the Poser black screen OpenGL problem and after emailing ATI was told it was most likely a Poser problem.

Well, as it turns out it isn't.

I decided to read through the release notes on the new Catalyst Control Center release and found this:

*"Official support for OpenGL 4.0 and OpenGL 3.3 ATI Catalyst 10.6 delivers official support for OpenGL 4.0 on the ATI Radeon™ HD5000 Series"

"Black screen no longer observed with "Unigine Heaven Benchmark 2.0" application with OpenGL mode settings" *