I am sorta relieved to see this post, NOT for you all going through this of course not,  but for my own sanity. I posted on this a month or so ago when first go Poser 8.  Noone understood and SmithMicro told me that I installed Poser 8 wrong.  Figured it out on my own to put the runtime files in with the Poser content folder in Documents.  

Now I have just got a new puter and reloaded everything, made sure to choose right option to install Poser 8, wanting to use external for runtimes.  Well it did the same thing, cannot load textures etc... Yeah, what a hassle.  Put everything in same Poser content folder which btw went into public documents again.

Am not going to mess with renaming them all, not until SR1 comes out and see if a fix is made. Works for now. Though I wanted them on external.  Hang in there hopefully they will fix this. :)