When I had Poser 5, the only way to cancel a render was CTRL ALT DEL because cancel render didn't work.

Poser 6 was better.  At least cancel worked. However, the time it takes to cancel largely depends on the bucketsize that is currently being processed. The larger the bucketsize, the longer it will take to cancel the render because Poser finished that bucket, before canceling.  Or at least that is my understanding.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi