Shockwave version 11 users
You do not need to "Open using Rosetta" as shown below (in fact you must unset it). If you are still having problems with Shockwave it is almost certainly because you previously set your machine to "Open with Rosetta". You should untick it.
Shockwave version 10 users
You can either upgrade to Shockwave 11 here or follow the instructions to "Open using Rosetta" as shown below.
From the horse's mouth
If you prefer, Adobe (who make Shockwave) have their own explanation here.
Intel Mac users with Shockwave 10
You should quit your browser before making this change.
Study (and print these instructions from the File menu if you wish) before closing this browser.
In the Applications folder, find the browser application you usually use (eg Safari, Firefox, etc.) and select it:
Choose Get Info from the File menu:
Make sure Open using Rosetta is ticked:
Close the Get Info box. Shockwave should now work in your browser.
