Believe it or not, this game was developed on a Mac, and as a Mac user I feel your pain about the problems in Shockwave with Mac OS X.
I have found that Safari has worked much better than Firefox in general. However, after 3 years of waiting it seems that the Mozilla team has finally fixed the screen redraw problem with Firefox, and the game works fine for me with the latest Shockwave (11.5.7.r603) and Firefox (3.6.8) on Mac OS X 10.6.4.
Is it just the game that isn't working or is it Shockwave itself?
Tester link: [www.adobe.com