We’re not Mac users here but I keep one around to stay current. Recently I attempted to upgrade the Flash player on our Mac to version 9. The software ran fine, but when the browser re-launched it was unable to detect the new player, rendering my system Flash-disabled. It turns out that I was not the only one. The fix is to run Application -> Utilities -> Disk Utility and choose the “Repair Permissions” for the main drive. Details are on the Macromedia Players Support Forum.