Here's a question... Can I move my Runtime to a different Drive and not have Poser freak out every time I try and open an older file that was created when the Runtime was on the previous drive? My Runtime is 932GB's, I need to move it to a larger Drive as the one it's on is almost full. Thanks in advance for any insights!

Everything that is related to a file in a runtime structure is saved using a relative, specific notation, it is not saved using an absolute path, so that yes, given the fact that you've instructed Poser where the runtimes lies now, there should not be any problem.
Just keep the runtime's structure intact.

Thanks Phil! 

Does this still apply using external libraries ?

I've remarkably little in P_11.3 'base' library on C:, but ~ 4 TB of assorted 'import' formats and external library runtimes on E: and G:

I link them in / out as needed. ( F: is mostly my non-CGI material.)

Saving a nice scene and render(s) with their makings makes it hard to re-arrange folders...

as long as you respect the path that's written in Poser's LibraryPrefs.xml file. If you are unsure to edit this text file, just remove the runtime reference from Poser's library manager and add it back by pointing it in its new location.

Thank you.