I have just installed the wp-photo-album-plus in my site and I have done a few tests and all is fine, but could not get the slideshow to work on Mac OX 10.5.8 (Intel ) Safari (5.0.3) and on Chromo (8.0).
It may be something I have done wrong since your demos (http://wppa.opajaap.nl/) work fine in all browsers.
Link to my site: http://www.santoestevaogolfe.com/?p=593&occur=1.
Can you please let me know what I have done wrong?
BTW Great Plugin