Thanks for the link because it made this one easier to troubleshoot…however, I just want to make sure that you have the style set as “preference” in the slideshow dropdown. Plus, that fact you uploaded the full “preference” widgetkit style to the plugin style folder? Also confirm that you have the Buttons set to “show”?
I just grabbed one of your slides and your caption you have for it and loaded it into my test site. When I mouse-over, I get the nav buttons showing in the lower right. I tried this in Chrome, Firefox, Safari, IE, and Opera.