At the risk of sounding like a simpleton...

An easy way to prove whether or not the problem is system related is to do a complete reformat and reinstall of the operating system. At that point the OS will be pristine. Then reinstall Poser and content (from the install files... NOT a backup.) 

I know you won't do this, but this is what it took for me to resolve a problem with Poser 7 lo these many moons ago. IT was worth the time to reinstall my 8000 plus content items.

I have had no problems with either P8 or PP2010 since the SR's.