More or less the same (stuttering) behavior with IE 7 and Firefox 2.0.0.20; Shockwave player version 11.5r471 according to http://www.adobe.com/shockwave/welcome and I’m running XP Pro x64. Now I’m kinda curious to see if Shockwave just doesn’t like this PC!
Also- minor aesthetic thing- on the last level, there’s the red spinning circles that show you what you need to shoot at; they work great when you’re looking at the things you need to shoot, but if you turn away then they collect around the edge of the screen. Come to think of it, that might be intentional? It looked odd at the time.
Otherwise- nice job; there are even a couple of physics puzzles in there (which I suppose is kind of the point!)