I too am having problems with the NextGen slideshow function – just acts as if it is loading. NG Gallery works fine in widget area (so i know it is accessing the gallery and i have the right ID), but the NextGen slideshow widget just keeps showing the spinning loading symbol.
Also tried to insert it in the body of the page (using the next gen button on page functions), but that doesn’t work either.
I use Firefox, but checked it on IE and it isn’t working there either. I also just updated the plugin to see if that worked – it didn’t.