First, set your preferred state to have no figures on stage.
and make sure you open to preferred state and use previous state. if you erase the P2 guy before you ever open Poser the first time after a fresh install, you may get the "out of memory" death notice.

If you have or wish to use NO stock characters or props I get by with the following

in Geometries:
deform
lights
props

in Textures:
Ground Default Texture.tif

in Libraries:
keep what you use

What ever Library files that you do use, you need their geometries and textures.

But if you use no Poser stock characters, props or hair
everything seems to work with just the above.

To say it another way:
If you must install a clean version of Poser 4 after a crash.
You only use 3rd party characters, clothing and props and you have their zips and exe's in backup.
What should I not delete if I do not wish to have problems with Poser's normal functions and requirements?