Don't delete anything!!!  First try reinstalling Poser and then changing the libraryprefs.xml like Karen suggested.

If you start deleting files, you may find yourself without working files period and having to reinstall a bunch of content.

"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