"It will list Shared folders and Shared Media, sometimes they take a couple of seconds to appear. "

This may be the problem. Doesn't happen, never happened. Only local resources (internal storage, SD card) in File Manager, ever. Hence my impression that the tablet wasn't capable of what seems to be a basic task, without installing some additional application.

Now I need to figure out why File Manager is broken. I'm starting to see a reflash in my future.