I have the identical problem and it's really starting to cripple my websites ans challenging my patience. In my case, I narrowed it down to the NGG slideshow not displaying as soon as I switch to a page with a sidebar option, be it a blog page or page template with the sidebar option. I tried it the perennial unisnt plugins routine and other tricks, but the problem still persists. I keep uninst/re-inst Flash and java on all my browsers, but still no dice - the issue occurs on IE, Firefox and Chrome, plus the problem can be intermittent and erratic. Very difficult to troubleshoot. This is the error message I receive:
This is exasperating!