http://www.adobe.com/cfusion/knowled...fm?id=6b3af6c9
Flash Player support on 64-bit operating systems
Issue
Flash Player is not supported for playback in a 64-bit browser.
However, you can run Flash Player in a 32-bit browser running on a 64-bit operating system.
Reason
Adobe is working on Flash Player support for 64-bit platforms as part of our ongoing commitment to the cross-platform compatibility of Flash Player. We have not yet announced timing or release dates.