I just spent a frustrating day trying to understand why files I had created for my former employer two years ago with loads of SWF files embedded in Acrobat Professional 6.0 were now NOT working properly in either Acrobat Reader 6 through 8 or Acrobat Professional 7.0.9.

The problem WASN'T the Shockwave Player or the Flash Player or the Trust Manager settings. It was a setting in QuickTime. I think by default, the "Enable Flash" setting is turned off in the Advanced tab of System Preferences > QuickTime. Once I clicked the check box, quit Acrobat and relaunched the application, my files worked perfectly again.

I'm using OS X 10.4.8, QuickTime Pro 7.1.3, Acrobat Pro 7.0.9, but I checked the QuickTime prefs on another computer here and sure enough, the "Enable Flash" setting wasn't turned on there, either. Be sure to make this change either in System Preferences > QuickTime > Advanced, or, if you're in the QT player, in QuickTime Preferences (not just Preferences) under the QuickTime Player menu. If you've already launched Acrobat or Reader, quit them and relaunch for the new QT settings to take effect.

Hope this saves someone the headaches I went through, but boy, what a relief!