Hi, apologies if this issue has already been reported. Also it would seem this plugin is no longer supported, which would be a shame because it does the job quite well.
But after installing it with the Twenty Ten theme, I found that it wasn't working properly. The relative div containing the slideshow had been placed by the plugin at the end of the footer, which meant that you had an unwanted div taking up empty space at the bottom of the screen, while the slideshow itself, being within an absolute div, was in the correct place at the top, except the rest of the page was simply collapsing underneath it, so the slideshow was covering the page content.
I can only guess that the "header-slideshow" div should have been placed in the header, rather than the footer. In the end I fixed it by removing the "header-slideshow" div altogether from header-slideshow.php and adding some top padding to the theme's header, so that the absolute div for the slideshow can fit in there nicely. But this is probably not the best solution, is it?