I want to report that all is well, after I followed Bagginsbill's meticulous run-through of potential issues and problems.

The solution (hanging my head in shame for not thinking of this in the first place), was to allow my firewall (McAfee) to allow Poser 9 as an exception.

As far as I can tell, a new virus definition or update from McAfee last night or this morning suddenly blocked access to program file.

Actually, I never would have figured it out without Bagginsbill's patient and thorough walk-through dissection of the issues. I also learned about my own system and have a better understanding of how to troubleshoot. Thank you, thank you.