I think this might be a factor in the 160-2203 issues people are getting. This is all just guesswork (haven't been able to run the newer builds, let alone replicate the issue!) but I'd say that this standalone RetroArch you guys keep mentioning has an incorrect method of loading a core on startup; which leads to the loader getting fed a bad RPX thus triggering the 2203. My best guess for the trigger at this point is the "libretro_path" section of the config files. Shadow's one looks like the following:
I would think that RA sees that path in the config and attempts to load the core, then (mumble mumble mumble mumble mumble) and the loader throws the 2203. For a quick acid test, can someone remove/clear/fiddle with that line in their config and see how RetroArch reacts? If it will work without loading a core on startup, then that narrows the bug right down.