At first, I suspected that it might have been caused by a Windows update, and one of its "malicious software removal tool", or something like that. With this in mind, just about 2 hours ago, I restored my system back 2 days. I rebooted, but the problem persists. 

Something else to keep in mind, I have been running Vue Esprit 9, sometime concurrently with Poser 9 (with no problem). Another program that might have been in conflict is Poser 4 and 5 (yes, lol) I still have those installed and sometimes use them for quick work. 

I have been opening files saved in Poser 4 or 5 and opening them with Poser 9. I've been doing that for several weeks, with no problems or issues. 

The only problem I have encountered was the incompatibility with Vue 9 (the SDK plugin is clearly not working for Poser 9).

At this stage, I am contemplating deleting and re-installing Poser 9. Since it's a recent install. I would not be losing a lot of work. I'm not sure it would resolve the issue.