OK, now I'm getting different symptoms. Any interruption of a Progressive Refinement render mid-sample is now giving me a screen render with some buckets complete for the current sample and others incomplete, with obvious ugly boundaries between them. More testing needed after a Poser restart...

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)