The libraries file doesn't show up until you have opened poser and accessed the library. After that it's found in "runtime/library/pref" Also, if the path to your runtime has changed since you last successfully used it, it is probably looking for the old location. Check and make sure that the drive is the same letter as what it was before you got the new computer.

"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