My several postings about not being able to get PowerDVD 9 Ultra to work *at all* (crashes, couldn't read any discs, etc) were, it turns out, caused by Comodo Firewall. I thought it *might* be that, and Googling it turned up this:
https://forums.comodo.com/defense_bugs/defence_conflicts_with_powerdvd_8_ultra-t39478.0.html
There's also this here:
http://forum.cyberlink.com/forum/posts/list/30/6039.page
So... my problems are solved. Sorry for all the grumbling - I was truly stumped!
- Tim