First of all, Alex Rabe, I have to tell your slideshow an gallery plugin is the BEST I've found. Thanks for the magnificent work you do!
I've been using your plugin for as long as a year with no problem so far. I upgraded to WP 2.8 and NextGen 1.3.3 and there was no problem until I upgraded to NextGen 1.3.4. Then I lost my slideshow. I realized later that I forgot to update the location of the imagerotator.swf file.
Then, everything worked perfectly!
Thanks, again, AlexRabe