You're right: re-installing PM didn't help, nor did going back to a previous version (4.4).
When the slideshow is hanging, I see a new application called SDL_app. I also notice that the initial slideshow pop-up window (with settings for auto-advance, delay, looping...etc.) takes longer to come up, perhaps indicating something is amiss even before the slideshow itself kicks off.
Not sure if this gives you any other ideas of what could be going wrong, or what else I could try to troubleshoot.
Thanks
Kevin