The slideshow is finicky at best.
In the default settings the images were speeding through the slideshow like crazy. So I changed the "Show each image for x seconds" from its default of 2seconds to 4 seconds. Then the slideshow did not advance at all. Manual advance worked. Now, a few restarts later it seems to work, but suddenly the slideshow does not start at all. All I get is a black screen. Esc gets me out of there and the next time things seem to work just fine.
:-(